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Molecular Physics
An International Journal at the Interface Between Chemistry and
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First-principles calculations to investigate
electronic, magnetic, and optical properties at
(110) and (111) surfaces of Ni adsorption on CdO
Qaiser Rafiq, Sardar Sikandar Hayat & Sikander Azam
To cite this article: Qaiser Rafiq, Sardar Sikandar Hayat & Sikander Azam (18 Apr
2024): First-principles calculations to investigate electronic, magnetic, and optical
properties at (110) and (111) surfaces of Ni adsorption on CdO, Molecular Physics, DOI:
10.1080/00268976.2024.2341117
To link to this article: https://doi.org/10.1080/00268976.2024.2341117
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MOLECULAR PHYSICS e2341117
https://doi.org/10.1080/00268976.2024.2341117
RESEARCH ARTICLE
First-principles calculations to investigate electronic, magnetic, and optical
properties at (110) and (111) surfaces of Ni adsorption on CdO
Qaiser Rafiq a, Sardar Sikandar Hayataand Sikander Azamb
aDepartment of Physics, International Islamic University, Islamabad, Pakistan; bDepartment of Physics, Riphah International University,
Islamabad, Pakistan
ABSTRACT
In this study, we utilised the GGA+U method via the WIEN2k software to investigate the structural,
magnetic, and optoelectronic responses of two distinct surfaces, (111) and (110), to Ni adsorption
on CdO at the Cd site. The analysis revealed that Ni/CdO (111) demonstrates properties akin to a
semimetal or a zero-gap semiconductor across both spin orientations, while Ni/CdO (110) exhibits
a metallic nature under similar conditions. These phenomena are predominantly ascribed to the
orbital contributions from Ni-d, Cd-d, and O-p for the Ni/CdO (111), and Ni-d, Cd-d, and O-s for
the Ni/CdO (110), respectively. A notable blue shift in the optical absorption spectra was observed
for both materials. Utilising the Dielectric function, we calculated the dispersion of energy bands
along with essential optical properties, including the absorption coefficient, energy loss function,
and reflectivity, refractive index, and extinction coefficient. Magnetisation values for Ni/CdO (110)
and Ni/CdO (111) were recorded at (−0.11794) µB and (2.17926) µB, respectively, influenced by the
absorption spectrum’s blue shift. Additionally, transport properties were evaluated using the Boltz-
TraP software over a temperature range of 0 to 800 K. Our findings suggest that Ni/CdO (110) and
Ni/CdO (111) are significant for applications in spintronics and energy devices.
ARTICLE HISTORY
Received 27 February 2024
Accepted 4 April 2024
KEYWORDS
Ni adsorption on CdO;
Properties;
electronic-magnetic-optical
response; surface properties
1. Introduction
In the contemporary era, the scarcity of potable water
represents a critical issue. The demand for clean
water has spurred various technological innovations
for its purication, notably in the realm of wastewa-
ter treatment [1]. The surge in global population has
necessitated the adoption of such treatments to enable
the recycling of wastewater [2]. Industrial discharges,
CONTACT Sardar Sikandar Hayat hi.sikander@gmail.com
particularly from the paper, textile, leather, and paint
sectors, are a primary source of water pollution, releas-
ing vast quantities of toxic, dye-laden euents. These
dyes obstruct sunlight penetration, adversely aecting
aquatic ecosystems and underscoring the need for strin-
gent environmental safeguards. The intricate molecular
congurations and chemical resilience of textile dyes
render traditional degradation methods such as coag-
© 2024 Informa UK Limited, trading as Taylor & FrancisGroup
2Q.RAFIQETAL.
ulation, occulation, and ltration ineective. Conse-
quently, enhancing current methodologies or devising
novel approaches remains a signicant hurdle in the eld
of wastewater management. Given the prohibitive setup
and operational costs, traditional methods are not feasi-
ble for either small or large industries. This scenario has
heightened the appeal of advanced oxidation processes
(AOPs), especially those employing metal oxide semi-
conductor photocatalysts, known for their rapid oxida-
tive capabilities.
Photocatalysis, a notable AOP technique, lever-
ages light (spanning the visible to ultraviolet spec-
trum) and semiconductor materials to dismantle dye
molecules. Noteworthy pollutants found in wastewater
include Methylene Blue (MB), Crystal Violet (CV), and
Rhodamine-B (RhB) [3–5]. Specically, CV, utilised in
various applications from Gram staining to leather dye-
ing, is identied as a persistent dye due to its degradation
resistance, presenting numerous ecological challenges
[6,7]. Investigations into photocatalytic processes have
focused on the employment of visible light-responsive
semiconductors like ZnO, NiO, CdO, and TiO2 nanopar-
ticles. Notably, cadmium oxide (CdO) is characterised
as an n-type semiconductor with a signicant band gap,
nding application in diverse areas including gas sensors,
photocatalysis, solar energy conversion, and biomedi-
caluses[8]. The process of doping CdO with various
metals enhances its ecacy in degrading environmental
pollutants. This technique, which involves introducing
dierent dopants, tailors the semiconductor’s properties
to specic needs, given each dopant’s unique attributes.
Studies by R. Aydina et al. on zinc and alkali metal-doped
CdO lms [9],andbyV.K.Guptaetal.onthephoto-
catalytic and antibacterial potentials of zinc-doped CdO
nanoparticles [10], highlight the material’s versatility.
Multi-element doping, compared to single-element
doping, oers a broader spectrum of property modi-
cations. For instance, silver doping creates a Schot-
tky barrier at the semiconductor interface, enhanc-
ing photocatalytic performance by minimising elec-
tron–hole recombination, extending electron lifespans,
and improving sensitivity to visible light [11–14].
Recent progress in materials science, exemplied by
the properties of Cs2AgFeCl6,hasunveiledpromising
prospectsinthermoelectricityandferromagnetism,lead-
ingtogroundbreakingapplicationsinadvancedmate-
rials [15]. Investigations into the piezoelectric, elec-
tronic, and thermodynamic characteristics of BiAlO3
and BiScO3have unveiled the versatile applications of
these materials, further broadening the scope of their
utility [16]. The identication of half-metallic ferro-
magnetism in Co2FeAl and Co2TiAl full-Heusler alloys
has underscored their potential in the eld of spin-
tronics, representing a pivotal advancement in the dis-
cipline [17]. Additionally, research into the structural,
electronic, optical, elastic, and thermoelectric properties
of quasi-two-dimensional BaFZnP has underscored its
potential as a catalyst for innovations in semiconduc-
tor technologies [18]. Moreover, employing comprehen-
sive DFT analyses with both GGA-PBEsol and TB-mBJ
functionals to study the attributes of CaCuP and CaAgP
Heusler alloys has shed light on their promising semi-
conductor behaviours. This is particularly notable for
their signicant ultraviolet absorption and conductiv-
ity, which are essential for advancements in optoelec-
tronic devices [19]. Cadmium oxide distinguishes itself
among semiconducting materials for its photocatalytic
prospects, despite limited exploration in this applica-
tion compared to other metal oxides like ZnO and TiO2
[20,21–23,24–27].
Within the scholarly domain, there has been consider-
able investigation into the optoelectronic characteristics
of CdO through a variety of experimental approaches.
Yet, investigations specically focusing on the optoelec-
tronic attributes of CdO surfaces with Ni adsorption,
particularly for Ni/CdO (110) and Ni/CdO (110) con-
gurations, employing density functional theory (DFT)
methods, are scarce. To our knowledge, the phenomenon
of Ni adsorption on CdO surfaces has not been previously
explored, prompting the initiation of this study due to
the apparent gap in systematic explorations of Ni’s opto-
electronic impact on CdO surfaces. The fundamental aim
of this study is to undertake ab initio calculations for an
in-depth analysis of the electronic, magnetic, and opti-
cal characteristics following nickel (Ni) adsorption on
cadmium oxide (CdO) surfaces, specically at the (110)
and (111) orientations. Utilising the advanced modi-
ed Becke–Johnson (mBJ) potential alongside density
functional theory (DFT) techniques with the GGA+U
method, our research endeavours to reveal changes in
electronic band structures, examine magnetic properties
via spin-polarized density of states analysis, and deter-
mine optical attributes through calculations of the com-
plex dielectric constant. The purpose of this work extends
beyond merely enhancing comprehension of the intrin-
sic properties of Ni on CdO surfaces; it aims to iden-
tify and underscore the potential applications of these
materials in the realms of UV optoelectronics, pho-
todetection, sensing technologies, and power electronic
devices, leveraging their distinctive electronic, magnetic,
and optical features. This paper is organised into sev-
eral sections for clarity and coherence. The rst section
introduces the study, setting the stage with relevant
background information. The second section details the
MOLECULAR PHYSICS 3
computational techniques and calculations that under-
pin our investigation. The third section is devoted to a
detailed examination and discussion of our ndings, cov-
ering the optoelectronic, structural, and magnetic char-
acteristics of Ni-adorned CdO surfaces.
2. Computational details
In this research, the WIEN2k software was utilised
for computational analysis [28]. Our study utilised the
Tran Blaha-modied Becke–Johnson (TB-mBJ) poten-
tial, which is recognised for its accuracy and moder-
nity in potential modelling [29]. This potential markedly
enhances the accuracy of band structure predictions,
ensuring alignment with experimental ndings. We
examined the structural and optoelectronic characteris-
tics of the Ni/CdO (110) and Ni/CdO (111) interfaces
using the full-potential linearised augmented plane wave
method within the framework of density functional the-
ory. The calculations for exchange–correlation energy
employed both the local density approximation (LDA)
and the generalised gradient approximation (GGA +U)
methodologies [30–41]. Additional information regard-
ing the advanced TB-mBJ method for the treatment of
exchange–correlation eects can be found in the cited lit-
erature [42]. Importantly, the TB-mBJ model is noted for
itsabilitytoproduceabandgapestimationthatissupe-
rior to that of PBE-GGA, oering a closer approximation
to empirical data.
Through linear perturbation analysis, the Hubbard U
parameter is meticulously determined, settling on a U
value of 4.0 eV. This selection facilitates a pronounced
division among the electrons in highly interactive envi-
ronments. The process of choosing the appropriate U
involves both tting and constrained methodologies,
where U is ne-tuned iteratively to align with the targeted
outcomes, thereby reducing the mean deviation across
the altered attributes [43]. For the computational settings,
an RKmax value of 7 is paired with a Gmax of 12 Bohr −1,
optimising the potential elds and instigating the cuto
for plane wave expansion of wave functions. Charge den-
sity calculations are carried out at a precision of 12 a0
−1,witha
0denoting the Bohr radius. Additionally, the
Brillouin zone is enhanced by 1000 k-points to ensure
thorough sampling. To accommodate the potentials and
charge density distributions, the mun-tin spheres and
the interstitial spaces are expanded to include angular
momenta up to l =10. The calculation process is iterated
until the convergence of total energy surpasses a thresh-
old of 10−4and the total charge convergence is within 0.1
mRy, guaranteeing precise determination of energy and
charge distributions.
For the structural modelling of (110) and (111)
surfaces, our approach involved generating an endless
sequence of slabs by cyclically duplicating a supercell in
three dimensions, aligning it appropriately. To minimise
interactions between these slabs, a vacuum separation
of 18 Å was introduced for both the (110) and (111)
surfaces.
The optimisation of each surface involved incremen-
tally adding layers until the energy required to split the
lm stabilised relative to the layer count. This stabil-
ity indicates that additional layers cease to signicantly
inuence the cleavage energy, as detailed in references
[44,45].
In this research, we extended the basic unit of CdO
into a larger (2 ×2×2) supercell containing 32 atoms
(16 each of CdO and Ni), enabling the simulation of
Ni adhesion on CdO surfaces. The placement of Ni was
strategically at a Cd site, achieving energy convergence
for the system at this specic adsorption site. For the
elements Cd, Ni, and O, the mun-tin (MT) sphere
radii were set to 2.0 Bohr. The Perdew–Burke–Ernzerhof
(PBE)-GGA method was applied for calculating the
exchange–correlation energy, a standard technique in
density functional theory for handling electron interac-
tions. To analyze thermoelectric characteristics like the
Seebeck coecient, power factor, electrical and ther-
mal conductivity, the BoltzTraP software was employed.
This tool leverages the semi-classical Boltzmann trans-
port theory, predicated on the electronic band structure
and assumes a consistent relaxation time. Our ndings,
as depicted in Figure 1, showcase the Ni adsorption on
a CdO substrate at the Cd position. Our exploration
intensies in the realms of computational approaches
and structural simulations pertinent to our study. Util-
ising the WIEN2k platform along with the Tran Blaha-
modied Becke–Johnson (TB-mBJ) potential exemplies
our dedication to employing state-of-the-art computa-
tional strategies for accurate delineation of electronic
structures. Notably, the TB-mBJ potential is esteemed
for its precision in predicting band gaps, aligning closely
with experimental data, and thus establishes a robust
groundwork for investigating Ni/CdO interface proper-
ties. The rigorous deployment of the full-potential lin-
earised augmented plane wave technique within the den-
sity functional theory (DFT) ambit facilitates a thor-
ough investigation of the structural and optoelectronic
attributes. Alternation between the LDA and GGA +U
approaches in computing exchange–correlation energy
enables a detailed comprehension of these attributes,
which is further honed by the deliberate calibration of
the Hubbard U parameter, enhancing electron localisa-
tion in areas susceptible to interactions. For structural
renement of the (110) and (111) surfaces, we generated
4Q.RAFIQETAL.
Figure 1. Crystallographic Representations for Ni/CdO (110) and
Ni/ CdO (111) Materials.
a continuum of slabs from a larger (2 ×2×2) supercell
conguration, meticulously simulating the Ni adsorp-
tion scenario. This simulation approach, alongside strate-
gic choices of computational settings like RKmax,Gmax,
and mun-tin spheres expansion, assures the veracity of
our simulation results. These detailed explanations are
intended to shed light on the sophisticated computational
and methodological framework anchoring our analysis of
Ni adsorption on CdO surfaces.
3. Results and discussion
3.1. Electronic properties
The bandgap stands as a critical physical parameter for
assessing the viability of semiconductors in photovoltaic
applications. As such, pinpointing the electronic struc-
ture of materials through the utilisation of precise and
suitable theoretical and experimental methodologies is
paramount. This process is integral for delineating the
scope of their potential applications.
3.1.1. Electronic band structure
Grasping the band gap energy of a material is crucial for
elucidating its characteristics and conductivity. Insights
into the material’s electronic band structure reveal the
energy levels that electrons inhabit and the transitions
they undergo between various bands [46].
At absolute zero temperature (T=0 K), employing
Generalised Gradient Approximation (GGA), GGA+U,
and modied Becke–Johnson GGA (mBJ-GGA) method-
ologies, we analyzed the spin-polarized band structures
of Ni/CdO in the (110) and (111) orientations. This
analysis was conducted at their equilibrium lattice con-
stants, following paths through high-symmetry direc-
tions in the rst Brillouin zone. The electronic energy
bands play a pivotal role in dening several critical
physical properties of solid materials. These proper-
ties include electrical conductivity, optical behaviour
(such as transmission, reection, and absorption of vis-
ible light), the nature of the band gap (direct or indi-
rect), and transport coecients. Evaluating the disper-
sion of these electronic energy bands allows for the
assessment of a material’s potential in various techno-
logical applications, including optoelectronics and ther-
moelectrics. Consequently, the investigation into the
electronic properties of materials emerges as a crucial
endeavour, necessitating the selection of a precise and
reliable theoretical framework for the examination of the
electronic band structure. In this context, we utilised
the advanced Full-Potential Linearised Augmented Plane
Wave plus local orbitals (FP-LAPW) method, incorporat-
ing both the Perdew–Burke–Ernzerhof for solids (GGA-
PBEsol) and Tran-Blaha modied Becke–Johnson (TB-
mBJ) functionals for exchange–correlation interactions.
This approach enabled us to compute the energy band
dispersions for Ni/CdO in both (110) and (111) cong-
urations, tracing an optimised trajectory that intersects
high-symmetry points within the rst Brillouin zone, as
depicted in Figure 2. These materials demonstrated pro-
nounced electron–hole mobility within their valence and
conduction bands, attributed to their signicant disper-
sionsinK-space.Attheoverlaplevel,electronsatthe
Fermi level are communally occupied between the two
bands, evidencing electron mobility from the valence
to the conduction band, attributed to the composition
of these materials with transition metals such as Nickel
(Ni), Cadmium (Cd), and Oxygen (O). This observation
suggests that the materials Ni/CdO (110) and Ni/CdO
(111) exhibit metallic properties across both spin con-
gurations. As shown in Figure 2, the Ni/CdO (110)
displays a crossing of both spin states’ valence and con-
duction bands at the Fermi level, revealing its metal-
lic nature. Conversely, the Ni/CdO (111) sees the con-
duction band’s intersection with the Fermi level in the
spin-up condition, pointing to a semi-metallic or zero
band gap semiconductor prole. In the spin-down sce-
nario, the conduction bands meet the Fermi level, with
the valence bands approaching it, further supporting the
semi-metallic or zero band gap semiconductor character-
istic. The metallic and semi-metallic properties of these
substances render them apt for diverse uses in opto-
electronics, spintronics, surface coatings, thermal solar
plants, and concentrated solar power (CSP) installations.
Particularly, the Ni/CdO (111) proves to be more e-
cient than its Ni/CdO (110) counterpart, attributed to its
MOLECULAR PHYSICS 5
Figure 2. Electronic Bandstructures for (a & b) Ni/CdO (111) for spin-Up/Dn and (c & d) Ni/CdO (110) for spin-Up/Dn Materials.
enhanced eciency in transitioning charge carriers from
the conduction to the valence band.
3.1.2. Density of states
The examination of electronic characteristics is eec-
tively conducted through the analysis of the density of
states (DOS), as noted in previous research [47]. To eluci-
date the characteristics of the electronic band structure of
each material, the total and partial densities of states were
determined using two distinct approximations: Gener-
alised Gradient Approximation (GGA) and GGA with
Hubbard correction (GGA +U), at their equilibrium
states. In our investigation, we performed spin-polarized
studies and found no magnetic ground states in undoped
CdO. Our focus extended to the electronic attributes of
Ni/CdO (110) and Ni/CdO (111) systems, for which the
spin-polarized DOS was calculated. The results, illus-
trated in Figure 3,revealapronouncedasymmetrical
distributionofDOSaroundtheFermilevel,armingthe
magnetic behaviour highlighted earlier.
To delve deeper into the inuence of Ni mono-
adsorption on CdO across two distinct surfaces, it is
6Q.RAFIQETAL.
Figure 3. Total and Partial density of States for Ni/CdO (111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials respectively.
essential to dissect both the total density of states (TDOS)
and partial density of states (PDOS). The TDOS eluci-
datesthecontributionstoPDOSfromindividualatoms,
especially within the energy spectrum of −12 eV to 12 eV.
For the Ni/CdO (110) conguration, the PDOS analysis
is bifurcated into two principal sections: from −12 to 0
eV and 0 to 12 eV. In the former section, notable contri-
butions are observed from Ni-d, Cd-d, and O-s orbitals,
whereas the latter section predominantly features contri-
butions from Ni-d, O-s, and O-d orbitals across both spin
orientations. Furthermore, the initial section includes
minor participations from Ni-d, Cd-d, and O-s orbitals,
while in the latter, contributions from Ni-s and Cd-d
orbitals are minimal for both spin directions. Analo-
gously, for the Ni/CdO (111) system, the PDOS prole
is similarly segmented, with the initial section showcas-
ing signicant input from Ni-d, Cd-d, and O-p orbitals,
and the subsequent section dominated by Ni-p, Cd-p, and
O-p orbitals for both spin congurations. Additionally,
the rst segment contains lesser contributions from Ni-
p, Cd-s, and O-s orbitals, and the subsequent segment
shows negligible input from Ni-s and Cd-d orbitals. The
comprehensive magnetic and electronic analyses under-
score the potential of this compound in applications
related to spintronics, optoelectronics, and paramagnetic
materials, as supported by reference [48].
To establish a relationship between the structural and
electronic characteristics of Ni/CdO (111) and Ni/CdO
(110) interfaces, one must examine the electron states
as revealed by the Density of States (DOS) charts across
varying energy levels. The electron states in proximity to
the Fermi level (EF) are particularly essential for deci-
phering magnetic characteristics, as a heightened DOS
at EFis indicative of potential magnetic activity, stem-
ming from the presence of unpaired electron spins. The
band structures delineate the energy of electrons relative
to their momentum within the material. In ferromagnetic
substances, the divergence in energy bands for opposite
electron spins near EFdenotes the existence of magnetic
moments.
Table 1details the magnetic moments for individual
atoms in the materials, oering a quantitative evaluation
of their magnetic tendencies. An atom with a measur-
able magnetic moment is indicative of its contribution
to the material’s overall magnetic prole. Comparative
analysis of the Ni/CdO (111) and Ni/CdO (110) inter-
faces unveils disparities in magnetic moments. There is a
discernible elevation in the aggregate magnetic moment
MOLECULAR PHYSICS 7
Tab le 1. Spin Magnetic Moments of Mixed Charge Density for
Ni/CdO (111) and Ni/CdO (110) Materials respectively.
Magnetic
Moment (µB)Material
Magnetic
Moment (µB)Material
µNi/CdO(111)Ni/CdO(111) µNi/CdO(110)Ni/CdO(110)
µCd10.00461 µCd10.00347
µCd20.00119 µCd20.00046
µCd30.00251 µCd30.00039
µCd40.00332 µCd40.00202
µCd50.03300 µCd50.03493
µO10.12292 µO10.00339
µO20.01353 µO2−0.00094
µO30.01281 µO30.00346
µO40.01657 µO40.03952
µO50.83311 µO50.82630
µO60.02776 µO60.00000
µNi 1.19163 µNi −1.02327
µinterstial −0.08370 µinterstial −0.00767
µcell 2.17926 µcell −0.11794
(µcell) for the Ni/CdO (111) surface relative to that of
Ni/CdO (110). These dierences likely arise from the
distinct crystallographic orientations, impacting the elec-
tronic structure as demonstrated by the DOS and band
structure visualisations.
Specically, Ni atoms on the (111) facet exhibit an
enhanced magnetic moment compared to those on the
(110) surface, which is attributable to variations in their
immediate surroundings and the interaction of Ni d-
orbitals with the orbitals of adjacent atoms. This interac-
tion is evidenced in the projected DOS (PDOS) graphs.
Additionally, the oxygen atoms display notable disparities
in magnetic moments across the two facets, potentially
resulting from varying degrees of hybridisation between
Ni d-states and Cd s-states.
The presence of a negative interstitial magnetic
moment in both instances implies an antiferromagnetic
interaction among certain moments within the lattice.
So, the structural distinctions between the (111) and
(110) planes lead to varied electronic states near the EF,
as illustrated by the DOS and band structure plots. These
variations in electronic states modulate the distribution
and orientation of magnetic moments across the two
interfaces. Also the cumulative magnetic moment of the
cell encapsulates the sum of individual atomic moments.
This cumulative moment is sensitive to the orientation of
the surface, which in turn is inuenced by the atomic con-
guration and bonding, ultimately shaping the magnetic
attributes of the interface.
3.2. Optical properties
The linear optical characteristics of a material in response
to incident electromagnetic waves are encapsulated by
the complex dielectric function, ε(ω)=ε1(ω)+
iε2(ω)[49]. In this function, the absorption of the
electromagnetic waves by the material is quantied by
the imaginary component, ε2(ω), while the real compo-
nent, ε1(ω), accounts for the radiation’s scattering within
the medium. The calculation of ε2(ω) is theoretically
based on the analysis of the momentum matrix elements
across lled and vacant wave functions [50,51], followed
by the derivation of ε1(ω)fromε2(ω)employingthe
Kramers–Kronig relations. From the real and imaginary
parts of the dielectric function, various linear optical
parameters, such as the refractive index n(ω), optical
reectivity R(ω), absorption coecient α(ω), and elec-
trical conductivity, can be directly determined [52,53].
These optical properties are pivotal for assessing multiple
critical parameters necessary for the categorisation and
application of materials in the realm of photovoltaics.
3.2.1. Complex dielectric function (real and imaginary
parts)
This research delved into the optical characteristics of
Ni/CdO (110) and Ni/CdO (111) materials to assess
their viability for application across various technological
domains, including optoelectronics, solar cells, photode-
tectors, light-emitting diodes, and telecommunications.
The scope of the investigation encompassed the energy
spectrumof0to14eV,duringwhichtheopticalattributes
of these materials were meticulously calculated. The out-
comes, depicted in Figure 4, present the derived optical
parameters across the aforementioned energy interval.
Essential optical parameters such as the dielectric func-
tion ε(ω), absorption coecient α(ω), refractive index
η(ω), energy loss function L (ω), extinction coecient
k(ω), reectivity R (ω), and optical conductivity were
determined utilising specic mathematical expressions
for both Ni/CdO (110) and Ni/CdO (111) congura-
tions across all photon energy levels, with foundational
methodologies and formulas sourced from references
[54,55–60].
ε(ω) =ε1(ω) +iε2(ω) (1)
α(ω) =√2ω−ε1(ω) +ε2
1(ω) +ε2
2(ω) −ε1(ω)1/2
(2)
η(ω) =1
√2ε2
1(ω) +ε2
2(ω) +ε1(ω)1/2
(3)
k(ω) =1
√2ε2
1(ω) +ε2
2(ω) −ε1(ω) 1/2
(4)
L(ω) =−In 1
ε=ε2(ω)
ε2
1(ω) +ε2
2(ω) (5)
8Q.RAFIQETAL.
Figure 4. Real and imaginary parts of complex dielectric functions for (a), (b), (c) and (d) Ni/CdO (111)-Spin-Up/Dn and Ni/ CdO (110)-
Spin-Up/Dn Materials respectively.
R(ω) =√ε1(ω) −iε2(ω) −1
√ε1(ω) −iε2(ω) +12
(6)
σ(ω) =2WCV h(ω)
Eo(7)
The following equations [61]canbeusedtocalculatethe
imaginary ε2(ω)andrealε1(ω) parts respectively, of
the dielectric function, ε(ω), for a cubically symmetric
material:
ε2(ω) =8
2πω2
nnBz |Pnn(k)|2dSk
∇ωnn(k)(8)
ε1(ω) =1+2
πP∞
0
ωε2(ω)
ω2−ω2dω(9)
Within the equations presented, the matrix element
Pnn(k)characterises the interaction among states within
the material. The term Sksignies the surface energy,
associated with the energy dierence ωnn(k)between
the nal and initial states, with P denoting the integral’s
principal component. Our investigation into Ni adsorp-
tion on CdO surfaces initially emphasises the signicance
of the dielectric function’s real and imaginary parts.
The real component of the dielectric constant signies
the capacity of the material to store electrical energy,
showcasing its response and polarizability to external
electric elds. On the other hand, the imaginary com-
ponent details the material’s absorption or dissipation
of energy within such elds, underscoring the inherent
energy losses. These elements are fundamental for elu-
cidating how electromagnetic waves interact with the
material, directly impacting the study’s focus on its elec-
tronic, magnetic, and optical characteristics. The elec-
tric polarizability, ε1(ω), illustrated in Figure 4for the
Ni/CdO (110) and Ni/CdO (111) systems, delineates the
dielectric function. At zero frequency, the static dielec-
tric constant, ε1(0), exhibits values of 3.5 and 2.8 for
Ni/CdO (110) and Ni/CdO (111) in the spin-up congu-
ration, and 6.9 and 12.2 in the spin-down conguration,
respectively. This discrepancy in ε1(0) values between
the materials is ascribed to variances in their band struc-
ture energies. Upon incrementing the frequency from
zero, ε1(ω)peaksatε1(ω)max values of 4.3 and 3.1
for Ni/CdO (110) and Ni/CdO (111) in spin-up states,
MOLECULAR PHYSICS 9
and 7.1 and 3.7 in spin-down states, respectively, before
decreasing and eventually inverting to negative at a pho-
ton energy of 13 eV. In regions where ε1(ω)isnegative,
both Ni/CdO (110) and Ni/CdO (111) for each spin state,
manifest metallic properties, rendering them eective
as electromagnetic radiation shields within these energy
parameters. The regions with negative ε1(ω) correspond
to reectivity maxima, indicating that with an increase
in energy, the magnitude of ε1(ω) diminishes, rendering
the materials opaque to higher-energy radiation.
The absorption dynamics of a material, especially the
transition from the valence to the conduction band,
is elucidated through the imaginary component of the
dielectric function, ε2(ω). For Ni/CdO (110) and
Ni/CdO (111), the imaginary parts of the dielectric func-
tion, ε2(ω), displayed in Figure 4, show threshold points
of energy transitions at 0.1 and 0.0 eV, and at 0.5 and
6.2 eV, respectively, for both spin states. These thresh-
olds, known as the fundamental absorption edges, indi-
cate electron transitions from Ni-d and Cd-d states in
the valence band to O-s, Ni-p, and O-p levels in the
conduction band. As energy increases, these fundamen-
tal absorption edges shift towards lower energy levels,
reectingvariationsinthebandgap.Notably,peaksin
the ε2(ω)max spectrum were recorded at energy levels
of 2.24 and 1.6 eV for Ni/CdO (110), and 4.24 and 8.8
eV for Ni/CdO (111), across both spin states. These
peaks, decreasing in magnitude and shifting to higher
energies, correlate with the narrowing of the valence
band width. In each spin state, these peaks are indica-
tive of electron transitions from Ni-d and O-p states in
the valence band to O-s and Cd-p states in the con-
duction band for Ni/CdO (110) and Ni/CdO (111),
respectively.
3.2.2. Refractive index
Data pertaining to the refractive index, η(ω), and the
extinction coecient, k (ω), of materials are crucial for
evaluating their optoelectronic characteristics, as eluci-
datedinpriorstudies[60–64]. These parameters play
a pivotal role in understanding the interaction between
light and material, providing insights into the optical and
electronic behaviour of the materials under investiga-
tion. The refractive index spectra, denoted as η(ω), for
Ni/CdO (110) and Ni/CdO (111) were derived and illus-
trated in Figure 5,basedontheincidentphotonenergy.
The trend observed in the η(ω)prolesmirrorsthechar-
acteristics of the ε1(ω) function. The peak values of the
refractive index, η(ω)max, along with the static refractive
indices, η(0), were identied as 2.39 and 1.92 for the spin-
Up state and 2.4 and 2.61 for the spin-Dn state in Ni/CdO
(110), and 1.8 and 1.61 for the spin-Up state and 2.21 and
3.7 for the spin-Dn state in Ni/CdO (111), respectively.
As depicted in Figure 5,bothη(0) and η(ω)maxvalues
exhibit a decline with an increase in energy, suggest-
ing the potential of Ni/CdO (110) and Ni/CdO (111)
for specic optical technologies. Beyond the η(ω)max the
refractive index, η(ω), diminishes and drops below one
upon reaching an energy threshold of 8.2 eV for both
Ni/CdO (110) and Ni/CdO (111) in both the spin-Up
and spin-Dn states. This phenomenon indicates a tran-
sition of the group velocity into negative values and the
material’s shift from linear to nonlinear behaviour. In
essence, this eect indicates that the materials exhibit
superluminal behaviour at high photon energies.
3.2.3. Extinction coefficient
Grasping the optoelectronic properties of materials is
essential for their application in technology. A key factor
Figure 5. Refractive Indexes for (a & b) Ni/CdO (111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials respectively.
10 Q. RAFIQ ET AL.
Figure 6. Extinctions Coefficients for (a & b) Ni/CdO (111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials respectively.
in this understanding is the extinction coecient, which
is integral to delineating these properties. As depicted in
Figure 6, the variation in the extinction coecients (k)
for Ni/CdO (111) and Ni/CdO (110) materials under dif-
ferent photon energy conditions is illustrated. The com-
puted refractive indices for Ni/CdO (111) and Ni/CdO
(110) stand at 0.55 and 1.5 for the Spin-Up state, and 0.64
and 1.05 for the Spin-Dn state, respectively, indicating
theirdistinctopticalresponses.
3.2.4. Reflectivity spectrum
The reectivity spectra, denoted as R (ω), for Ni/CdO
(110) and Ni/CdO (111) across both spin orientations
were calculated and presented in Figure 7. The ini-
tial reectivity values, R (0), alongside their peak val-
ues, R(ω)max, were established to be 0.10 and 0.14 for
the Spin-Up and 0.20 and 0.23 for the Spin-Dn states
in Ni/CdO (110), and 0.058 and 0.08 for the Spin-Up
and 0.06 and 0.04 for the Spin-Dn states in Ni/CdO
(111), respectively. It was observed that R (0) tends to
increase as the energy spectrum broadens. The peak
reectivity,R(ω)max was noted to occur at energy lev-
els exceeding 13 eV for both materials in each spin
state. Notably, at these energy levels, the value of ε1(ω)
becomesnegative,suggestingatransitiontoametallic
phase for both Ni/CdO (110) and Ni/CdO (111) in all
spin congurations.
3.2.5. Absorption coefficient
Understanding the impact of external constraints on the
electronic structure of solid-state materials necessitates
the calculation of their optical conductivity, a process
Figure 7. Reflectivity Spectrum for (a & b) Ni/CdO (111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials respectively.
MOLECULAR PHYSICS 11
Figure 8. Absorption Coefficients for (a & b) Ni/CdO (111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials respectively.
detailed in the literature [62–65]. This approach is funda-
mental in dissecting the intricate ways in which such con-
straints inuence the optical and electronic properties of
these materials. As depicted in Figure 8, it is evident that
absorption at lower energy levels is primarily attributed
to transitions among closely aligned energy states. How-
ever, within the energy spectrum of 6.0 eV to 13.0 eV, pro-
nounced peaks are observed for both Ni/CdO (110) and
Ni/CdO (111) materials across both spin congurations.
Following this energy interval, there is a gradual decline
in absorption, culminating in a prole characterised by
multiple minor peaks.
3.2.6. Energy loss function
Figure 9depicts the mechanisms contributing to pho-
ton energy loss, which include phonon–electron scat-
tering, dispersion, and thermal eects. Notable peaks
in energy loss at the plasmonic frequency indicate the
prevalence of signicant plasmonic activity. Typically, the
main peak observed in the L (ω)spectrumiscorrelated
with the plasma frequency [66]. In the lower energy spec-
trum, these materials exhibit minimal energy loss along-
side pronounced absorption of electromagnetic radia-
tion. Such features render Ni/CdO (110) and Ni/CdO
(111) materials advantageous for use in infrared (IR)
technology applications, where the eective absorption
of IR radiation is benecial.
3.2.7. Optical conductivity (real and imaginary parts)
The inuence of external variables on the electronic
structures of solid-state materials is highlighted through
theanalysisoftheiropticalconductivity.Figure10 show-
cases the variability in optical conductivity with changes
in incident photon energy levels, with a focus on Ni/CdO
(111) and Ni/CdO (110) substances. This illustration
provides insight into both the real and imaginary seg-
ments of optical conductivity for these substances. Gen-
erally, the real components of their optical conductivities
start above zero, with Ni/CdO (110) exhibiting the most
signicant initial value. Conversely, the imaginary ele-
mentsoftheiropticalconductivitiessetobelowzero,
diminishing prior to their convergence at one. The pres-
ence of non-zero optical conductivities within the vis-
ible light spectrum underscores the suitability of these
materials for optoelectronic applications, indicating their
utility in this technology domain.
3.3. Magnetic properties
The characterisation of materials, including metals,
semimetals, insulators, and semiconductors, necessitates
acomprehensivegraspoftheirelectronicbandstruc-
ture. Utilising the Generalised Gradient Approximation
(GGA), the magnetic characteristics of Ni/CdO (110)
and Ni/CdO (111) materials were evaluated. The ndings
relatedtothespinmagneticmomentsandtheinterstitial
moments within a spherical region for Ni/CdO (110) and
Ni/CdO (111) at equilibrium lattice parameters, based on
both GGA and GGA +U methodologies, are presented
in Table 1. Over the last ten years, comprehensive investi-
gations have been conducted into transition metals across
multiple disciplines, with a signicant focus on the devel-
opment of sensors employing materials exhibiting giant
magneto-resistance (G-MR). This includes both inor-
ganic and organic materials. G-MR sensors are pivotal in
a variety of applications such as linear and angular posi-
tion detection, electric current measurement, biosensing,
non-volatile magnetic storage, magnetic eld detection,
12 Q. RAFIQ ET AL.
Figure 9. Energy Loss Functions for (a & b) Ni/CdO (111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials respectively.
Figure 10. Real and imaginary parts of optical Conductivities for (a), (b), (c) and (d) Ni/CdO (111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-
Up/Dn Materials respectively.
MOLECULAR PHYSICS 13
aerospace technologies, energy systems, healthcare, con-
temporary transportation, and data recording technolo-
gies [67]. This underscores the importance of these sen-
sors and the magneto-resistive properties of the materials
used in them, drawing widespread interest.
In our investigation, we have applied the GGA +U
method with a specic parameter (U =4eV) to enhance
the localisation of transition metals like Cadmium (Cd)
and Nickel (Ni). This approach has allowed us to delve
deeper into the magnetic characteristics of Ni/CdO (110)
and Ni/CdO (111) compounds. Through spin-polarized
analysis, we have forecasted the magnetic nature of these
compounds. The estimation of the magnetic moment,
a key magnetic parameter, was conducted to compre-
hend the behaviour of these materials. The magnetic
moments for the Ni/CdO (110) and Ni/CdO (111), along
with those of their individual atoms, have been calcu-
lated using the GGA +Utechnique,withthendings
summarised in Table 1.TheanalysisofTable1demon-
strates that the Ni/CdO (111) compounds possess higher
magnetic moments than the Ni/CdO (110) compounds,
suggesting that they function as robust ferromagnets.
The Nickel (Ni) atoms, forming adsorbed clusters on
the CdO surfaces, primarily contribute to the overall
magnetic moment. It is notable that solely the Nickel
(Ni) atoms exhibit ferromagnetic characteristics, whereas
other atoms such as oxygen (O) and Cadmium (Cd) are
diamagnetic. A signicant observation from our study
is the persistence of ferromagnetic properties in Nickel
(Ni) atoms when adsorbed onto the CdO (111) sur-
face, rendering the Ni/CdO (111) compound ferromag-
netic. Conversely, this magnetic property is absent when
Nickel (Ni) atoms are adsorbed on the CdO (110) sur-
face, resulting in the Ni/CdO (110) compound exhibiting
diamagnetic behaviour.
3.4. Thermoelectric properties
Thermoelectric (TE) materials are pivotal in the direct
conversion of thermal to electrical energy, highlighting
their importance and drawing increased research focus
on their properties. These materials nd application in
various domains, including thermoelectric cooling, com-
putational device temperature regulation, and compo-
nents in small-scale detectors. Materials with thermo-
electric (TE) properties exhibit a remarkable capability
to convert waste heat into usable energy. The Boltz-
TraP software [68], utilises Boltzmann transport the-
ory as its foundation for computations. It is capable
of determining various properties of materials includ-
ing electronic thermal conductivity, electrical conduc-
tivity, the Seebeck coecient, and the power factor. For
a material to possess potential thermoelectric capabili-
ties, it is essential to have high electrical conductivity,
a substantial Seebeck coecient, and minimal thermal
conductivity. The study of Ni/CdO (110) and Ni/CdO
(111) as prospective thermoelectric materials involves
analyzing variations in electrical and thermal conduc-
tivities, the Seebeck coecient, and the power factor
with temperature changes. These parameters are cru-
cial for understanding the performance and eciency
of TE materials under varying thermal conditions. This
research employs a synergistic approach using the gener-
alised semi-classical BoltzTraP code alongside the rigid
band approximation, grounded on evaluations of the
local densities of states and band structures [69]. The
thermoelectric characteristics are assessed across a broad
temperature range (200–800 K) to explore their thermal
behaviour.
3.4.1. Electrical conductivity
The ow of free charge carriers is evaluated through
electrical conductivity measurements, as depicted in
Figure 11, showcasing the electric conductivity (σ/τ)
plots for both Ni/CdO (110) and Ni/CdO (111) materi-
als over an extensive temperature spectrum. For Ni/CdO
(110) materials, there is an observed increase in elec-
trical conductivity from 1.0 ×1020 ms−1to 1.3 ×1020
ms−1in the temperature interval from 200K to 250K.
This increase is likely due to the thermal activation facil-
itating electron transitions from the valence to the con-
duction band. The electrical conductivity’s sensitivity
to the band structure plays a crucial role in thermo-
electric properties. A linear trend is noted from 250K
to 800K, with electrical conductivity diminishing from
1.8 ×1020 ms−1to 9.0 ×1019 ms−1over the com-
plete temperature range of 200 K to 800 K for both spin
Figure 11. Electrical Conductivity for (a), (b), (c) and (d) Ni
/CdO (111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials
respectively.
14 Q. RAFIQ ET AL.
states. Conversely, for Ni/CdO (111) materials, electrical
conductivity rises from 3.0 ×1019 ms−1to 4.1 ×1019
ms−1and from 1.8 ×1019 ms−1to 2.1 ×1019 ms−1
for both spin states across the 200K to 800K temper-
ature span, respectively. The notable anharmonicity in
these materials suggests that anharmonic phonon inter-
actions may signicantly inuence the observed con-
ductivity behaviours [70]. The presented data, illustrat-
ing the temperature-dependent electrical conductance of
Ni/CdO on both (111) and (110) facets for distinct spin
orientations, demonstrates a notable constancy in con-
ductance over an extensive thermal spectrum, with an
emphasis on the (110) orientation. Such ndings infer
the potential ecacy of Ni-doped CdO in thermoelec-
tric contexts, necessitating consistent electrical conduc-
tance amidst uctuating thermal conditions, applicable
to energy harvesting from thermal waste or the detection
of thermal gradients.
3.4.2. Thermal conductivity
Lattice vibrations, represented by phonons, and elec-
trons are primary factors inuencing heat transfer within
materials. In semiconductors, phonons notably dom-
inate thermal conduction processes, whereas in met-
als, the contribution of free electrons to thermal con-
ductivity is more signicant [71]. Figure 12 presents
the thermal conductivity data for Ni/CdO (110) and
Ni/CdO (111) materials. For both spin congurations,
these materials demonstrate a pronounced increase in
thermal conductivity as the temperature escalates. At the
starting temperature of 200 K, the thermal conductiv-
ity is recorded at approximately 5.2 ×1014 (W/mks) and
4.8 ×1014 (W/mks) for Ni/CdO (110), and 2.3 ×1014
(W/mks) and 2.2 ×1014 (W/mks) for Ni/CdO (111),
respectively. A marked augmentation in thermal con-
ductivity is observed beyond ambient temperatures, as
Figure 12. Thermal Conductivity for (a), (b), (c) and (d) Ni/CdO
(111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials
respectively.
depicted in Figure 3.Reachingapeakat800K,the
thermal conductivity values ascend to about 1.8 ×1015
(W/mks) and 1.4 ×1015 (W/mks) for Ni/CdO (110),
and 2.6 ×1014 (W/mks) and 4.8 ×1014 (W/mks) for
Ni/CdO (111), for both spin states, respectively. This
evidence suggests that both Ni/CdO (110) and Ni/CdO
(111) materials maintain commendable thermal conduc-
tivity across the entire temperature range investigated.
The graphical representation of thermal conductance for
Ni/CdO on both (111) and (110) surfaces, with respect
to dierent spin states, shows a positive correlation with
temperature. This indicates the potential for tailoring
Ni/CdO for use in thermoelectric modules and thermal
management devices, where modulated thermal conduc-
tivity is advantageous, particularly in environments that
demand stability at elevated temperatures.
3.4.3. See-beck co-efficient
The performance of thermocouples is quantitatively
assessed through the Seebeck coecient (S), which quan-
ties the relationship between the generated voltage dif-
ference and the temperature gradient [72]. Figure 13
displays the Seebeck coecient values for Ni/CdO (110)
and Ni/CdO (111) materials. Initially, at 200 K, the
peak values of the Seebeck coecient for Ni/CdO (110)
and Ni/CdO (111) materials span 1.1×10−5(V/K),
−2.9 ×10−5(V/K), 0.3 ×10−5(V/K), and 1.8 ×10−5
(V/K) for both materials in each of the two spin states,
respectively. With an increase in temperature, the See-
beck coecient decreases to a stable value at elevated
temperatures. This behaviour underscores the critical
role of the Seebeck coecient in determining the ecacy
of thermocouples, providing a direct linkage between
thermal gradients and generated electrical signals. The
observed trends in the Seebeck coecient with tem-
perature variations oer insights into the thermoelectric
conversion eciency of these materials. The observed
variance in the Seebeck coecient for Ni/CdO across the
(111) and (110) orientations, when comparing spin-up
to spin-down states, suggests the potential for customis-
ing Ni/CdO for sophisticated thermoelectric uses. These
include electricity production and cooling processes,
where the spin-related transport characteristics may con-
tribute to heightened control and improved operational
eciency.
3.4.4. Power factor
Inouranalysis,weomitthegureofmerit(ZT)duetothe
absence of lattice thermal conductivity measurements.
Instead, we focus on the power factor (PF), dened as
PF =σS2, which serves as a critical metric for evaluat-
ing the transport properties of materials [73]. Materials
with high PF values are particularly advantageous for
MOLECULAR PHYSICS 15
Figure 13. Seebeck-Co-efficient for (a), (b), (c) and (d) Ni/CdO
(111)-Spin-Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials
respectively.
applications where space is limited, as they can eciently
convert temperature dierences into additional energy.
For the Ni/CdO (110) and Ni/CdO (111) compositions,
thereisanotableincreaseinthepowerfactorwithtem-
perature elevation. Initially, at 200 K, the power factors
for both materials in each spin state are approximately
1.26 ×1010 (W/mK2s), 0.3 ×109(W/mK2s), 0.4 ×109
(W/mK2s), and 5.0 ×109(W/mK2s) for Ni/CdO (110)
and Ni/CdO (111), respectively. The Ni/CdO (110) mate-
rial experiences a signicant decrease in power factor, fol-
lowed by a consistent linear trend up to 800 K, reaching a
value of 2.23 ×109(W/mK2s) for the spin-up state, while
maintaining a linear increase to 0.7 ×109(W/mK2s) for
the spin-down state at 800 K. Conversely, the Ni/CdO
(111) material demonstrates a continuous increase in
power factor up to 800 K, with a value of 2.23 ×109
(W/mK2s) for the spin-up state. The power factor for
the spin-down state initially rises before diminishing at
800 K, recorded at 0.7 ×109(W/mK2s). As depicted in
Figure 14, the distinctive power factor trends for both
Ni/CdO (110) and Ni/CdO (111) suggest their poten-
tial utility in various technological applications, such as
in thermoelectric generators and cooling systems, albeit
with a focus on their aptness primarily for thermal man-
agement devices. The exhibited data on the Power Factor
for Ni/CdO across the (111) and (110) crystal planes,
which display divergent spin states, indicate a marked
disparity in their thermal electric performance. Notably,
the (111) facet with spin-up orientation demonstrates
an exponential enhancement in response to tempera-
ture increments. Consequently, this positions Ni/CdO as
a viable candidate for thermoelectric roles that operate
at elevated temperatures, including but not limited to,
thermal-to-electrical energy conversion and the collec-
tion of thermal energy, where an elevated Power Factor
plays a pivotal role in operational ecacy.
Figure 14. Power Factor for (a), (b), (c) and (d) Ni/CdO (111)-Spin-
Up/Dn and Ni/ CdO (110)-Spin-Up/Dn Materials respectively.
In assessing the relative eciency across dierent sur-
faces and spin congurations for Ni/CdO (111) and
Ni/CdO (110), a comprehensive analysis of the interplay
between electrical and thermal conductivities, alongside
the Seebeck coecient, is critical. These factors together
contribute to the power factor, which is derived from the
product of the Seebeck coecient squared and the elec-
trical conductivity, normalised by the thermal conductiv-
ity. An optimal thermoelectric performance is expected
wherethereisanelevationinpowerfactor,notably
observed in the (111) surface with spin-Up, particularly
at heightened temperatures where this metric notably
escalates. While the (110) surface exhibits consistent high
electrical conductivity with spin-Up, its power factor
enhancement with temperature is less pronounced, sug-
gesting a comparatively suboptimal eciency relative to
the (111) surface with spin-Up in elevated thermal con-
ditions. The synthesis of these factors, reected in the
power factor graph, identies the (111) surface with spin-
Up as the superior performer at temperatures surpassing
roughly 500 K, where it achieves the apex of power factor
values.
4. Conclusion
Inourstudy,weappliedthemodiedBecke–Johnson
(mBJ) potential in conjunction with density functional
theory (DFT) using the GGA+Uapproachthroughthe
WIEN2k framework to thoroughly examine the opti-
cal, electronic, structural, and thermoelectric character-
istics of Ni/CdO surfaces (110) and (111). Our ndings
demonstratethattheintegrationofthemBJpotential
markedly enhances the electronic band structure of both
variants, eectively overcoming the shortcomings inher-
ent in the traditional LDA and GGA methods by closing
16 Q. RAFIQ ET AL.
the initially small band gap. A comprehensive examina-
tion revealed that the electron orbitals of Ni-d, Cd-d,
and O-s (or O-p in the case of Ni/CdO (111)) predom-
inantly inuence the valence and conduction bands in
both spin orientations, signicantly impacting the mate-
rials’ magnetic properties as indicated by spin-polarized
density of states (DOS) analysis. The investigation into
optical properties, through the calculation of the complex
dielectric constant ε(ω), uncovered substantial absorp-
tion strength within the 6.0 eV to 12 eV energy spec-
trum, identifying these materials as viable options for
ultraviolet region-focused device applications. Further-
more, our analysis into thermoelectric behaviour reveals
that Ni/CdO (111) possesses lower electrical and thermal
conductivities in contrast to Ni/CdO (110), however, it
boasts a more advantageous power factor, indicating a
predilection for Ni/CdO (111) for use in technological
advancements. The synthesis of our research underscores
the unique benets of utilising Ni/CdO (111) in the
realms of UV optoelectronics, photodetection, sensing,
and power electronic applications, marking a progressive
leap in materials science. This study not only deepens
the comprehension of Ni/CdO compounds’ fundamen-
tal properties but also establishes a critical benchmark for
subsequent theoretical and practical investigations aimed
at the creation of sophisticated electronic and energy-
oriented devices.
Disclosure statement
No potential conict of interest was reported by the author(s).
ORCID
Qaiser Raq http://orcid.org/0009-0003-9085-3444
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