Solid State Physics - Science topic

The basic scenario where the graph is exponential and we may extrapolate to obtain the bandgap in eV is suggested in research publications on energy bandgap approximation using Tauc Plot. Which peak, however, should I take into account for extrapolation when there are multiple peaks in a Tauc Plot?

The appropriate figure is included.

In this model, the number of density of available states for the charge carriers near Fermi level comes around 10^22. Will this much number come for bulk insulating ceramics. For the calculation of number of density of available states for the charge carriers near Fermi level, f0 (resonance frequency) is taken as 10^13Hz. Why? Could you please help me.

Do you consider yourself a real scientist in your field?

As for me, I don't because I don't know the answer of many basic questions in solid-state physics. For instance, from what's the energy origin of orbitalizing electrons? Is is the thermal energy at T>0 or some sort of quantum energy or both? What's exactly the group velocity of orbitalizing electronic waves and its relation to the ground state energy and thermal energy near T=0. I know there exist so many formal definitions of all the above terms! But is the exact relation between them? In particular, the quasi-free electrons in the conduction band (at T>0) what is exactly the nature of their (so-called) velocity in equilibrium, in the inter-collisional paths (between successive scattering with atoms )? Is is just their thermal velocity? or combination of this thermal velocity with some sort of quantum energy?

I am trying to calculate Band structure for the electrode in Siesta. It is a supercell as it should be. Can any one tell me how to unfold the degenerate bands in band structure plot so that I can compare it with transmission?

Hi,

Is anharmonicity in the phonon will reduce the Tc of that material?

I found in some of A-15 compounds anharmonic effects will be more.  Can these effects will lead to increase in the Tc or Decrease in the Tc?

Thanking you.

Dear R^G community members, in this thread, I will discuss the similitudes and differences between two marvelous superconductors:

One is the liquid isotope Helium three (³He) which has a superconducting transition temperature of T_c ~ 2.4 mK, very close to the absolute zero, it has several phases that can be described in a pressure - P vs temperature T phase diagram.

³He was discovered by professors Lee, Oshero, and Richardson and it was an initial point of remarkable investigations in unconventional superconductors which has other symmetries broken in addition to the global phase symmetry.

The other is the crystal strontium ruthenate (Sr₂RuO₄) which is a metallic solid alloy with a superconducting transition temperature of T_c ~ 1.5 K and where nonmagnetic impurities play a crucial role in the building up of a phase diagram from my particular point of view.

Sr₂RuO₄ was discovered by Prof. Maeno and collaborators in 1994.

The rest of the discussion will be part of this thread.

Best Regards to All.

What are the books/articles to study the crystal structure of nanoferromagnetic materials?

I am looking for research articles, which describe the synthesis process of Mn₃O₄ thinfilm on a substrate by a spin coating method.

Material Characterization, Solid State Physics, Surface Science, Spectroscopy, Diffraction

when a 2DEG is subjected to the magnetic field, the energy is split in the form of Landau levels. and the QHE is explained on that basis. however, in the case of quantized resistance is obtained without a magnetic field. then how Landau levels are formed in QSHE?

In non-local measurements, we apply current between two leads and measure voltage on different leads away from the current leads. to calculate resistance, do we need to divide the non-local voltage by current - as such current is not flowing through the voltage leads?

can you please suggest good literature on non-local measurements?

Thanks

I have several confusions about the Hall and quantum Hall effect:

1. does Hall/QHE depend on the length and width of the sample?

2. Why integer quantum Hall effect is called one electron phenomenon? there are many electrons occupying in single landau level then why a single electron?

3. Can SDH oscillation be seen in 3D materials?

4. suppose if there is one edge channel and the corresponding resistance is h/e^2 then why different values such as h/3e^2, h/4e^2, h/5e^2 are measured across contacts? how contact leads change the exact quantization value and how it can be calculated depending on a number of leads?

5. how can we differentiate that observed edge conductance does not have any bulk contribution?

When a material is in a Topological state, the conduction in 2D TI is due to the edge channel. If I am using a Hall bar structure where I am doing Non-local measurements as can be seen from the attached file. Many papers say that there is edge conductance of h/e^2 corresponding to one edge channel. If in a Hall bar there are 6 terminals. this is distributed as 1:5 and each channel show h/6e^2 resistance. I do not understand why there is only h/6e^2 resistance even though voltage measurement is done at one terminal? please help

What are the quantum materials? Quantum phenomenon takes place in every material at atomic level. then how to define quantum materials? is Iron (magnetic materials) quantum material as it shows magnetism which is the quantum phenomenon? if not then what are quantum materials?

Has anyone encounter Bratu equation (1D second order differential equation) in electronics, solid state physics or optics problems? So far I am aware that Bratu equation is found in chemical combustion problem.

Generally, we always try to give low input to operate a device. What are the minimum values of voltage for CMOS technology and magnetic field for spintronics technology?

Dear and Distinguished Fellows from the solid-state physics R^G community.

Does have anyone read after 20 years the preprint from Prof. Laughlin A Critique of two metals?

I read it when I was a PhD student. I think his opinion after 20 years deserves more attention. Please, feel free to follow down the link to the arXiv preprint if somebody has an interest and please leave your opinion:

Theoretical calculation of electrons in spin down states of half and full heusler alloys.

Just curious to make a list of recommended books/study materials explaining Magnetism in condensed matter physics preferably with emphasis on Quantum Magnetism.

I would be glad if you give some references from Bachelors to Ph.D. level.

Thanks & Regards,

KP

Does electron mobility only depend on the presence of an electron in the conduction band, or low band gap? Please explain.

In the (electro-) conducting materials, as I know, there is an energy gap between the valence band (VB) and the conduction band (CB) that can be brought to or near-to the Fermi level by doping (p-type or n-type dopant).

But ( My question is ), If I want to design a (semi- or super-) conductor's materials (inorganic or polymeric) , Which properties would I look for? and, also, Which characterizations would I consider for the properties' investigations? What are the requirements for the materials' property (with regard to its band structure) to achieve the considered structure-property relationships (or requirements ) for the preparation of the conducting materials?

Dear R^G community, this review thread is about the role of RKKY interaction in solid-state physics. I want to learn more about it. I would like to know for example, what physics effects RKKY describe well.

In rare-earth metals, whose magnetic electrons in the 4f shell are shielded by the 5s and 5p electrons, the direct exchange is rather weak and insignificant and indirect exchange via the conduction/itinerant electrons gives rise to magnetic order in these materials.

[1] M.A. Ruderman and C. Kittel, Phys. Rev. 96, 99 (1954).

[2] T. Kasuya, Prog. Theor. Phys. 16, 45 (1956).

[3] K. Yosida, Phys. Rev. 106, 893 (1957).

[4] D. I. Golosov and M. I. Kaganov, J. Phys.: Condens. Matter 5, 1481-1492 (1993).

[5] http://sciencewise.info/definitions/RKKY_interaction_by_Vadim_Cheianov.

[6] http://www.cmp.liv.ac.uk/frink/thesis/thesis/node71.html

Spin orbit torque (SOT) switching of ferromagnetic layer with perpendicular (Out-of-plane) magnetization requires an additional in-plane magnetic field along the direction of applied charge current.

Could any one please give a lucid explanation for the need of such in-plane magnetic field and also please explain symmetry of which is broken by this applied field?

What is the Exciton's Bohrs Radius? of :

- Boron Nitride (BN)

- Graphite

Anyone know ?,

Or have seen one of these in a paper ?

I'll appreciate it !

Regards !:)

The term Condensed Matter is a synonym of Solid-state Physics. Recently, many scientists and researchers replaced their field of specialty and use the term Condensed matter, with its two branches (Soft and hard Condensed matter Physics) to identify weakly-coupled and strongly coupled materials. However, condensed mater includes solids and liquids. If you are interested in these topics, which term you prefer (e.g., to talk about superconductors) and why?

Hello all

I am currently working on lead halide perovskites that are bromine-based. The issue with my material is that it falls out of phase very quickly under ambient settings, and I am trying on ways to keep it more stable, such that its PL also does not degrade. Any suggestions on how I can solve this problem?

Hi There,

I am doing a simulation in COMSOL to find the carrier concentrations in an abrupt p-n junction. The donor and acceptor concentrations are (Nd=3*10^26, Na=10^24) respectively. Unfortunately, there is a mismatch between theoretical and simulated results.

Please read the attached document carefully to understand my question.

Generally, when we calculate the carrier density in 2DEG from SdH oscillations (Field dependence of sheet resistance) and QHE (field dependence of Hall resistance) it should match. In some cases it was found that carrier density calculated using both data differ. What is the reason behind this difference? What is the physics behind the calculation of carrier density from SdH oscillations and Hall resistance data?

i have taken structural mechanics

solid state physic

my design is rectangle shape cantilever.one end fixed and another end will be free.

Dear R^G community, the unitary limit in the amplitude of dispersion * in QM is very complicated and elusive to explain, although there are firmly pieces of evidence, that unconventional superconductors such as HTCSs and Heavy Fermions are mostly in the strong scattering unitary limit at very low energies (temperatures) and a certain range of dopping by non-magnetic impurities. There are also pieces of evidence that point to the same conclusion in Fermi & Bose atomic gases ^~,#.

We will publish a preprint on this topic.

I will showcase 3 references in this thread, for now:

* 1. Quantum Mechanics (non-relativistic theory) Landau & Lifshitz, Chapter XVII on elastic collisions, Pergamon, 1977.

⁺ 2. Superfluid Fermi liquid in a unitary regime by L. P. Pitaevskii, arXiv & Physics - Uspekhi v. 51 p. 603 (2008).

^# 3. Momentum-resolved spectroscopy of a Fermi liquid E. Doggen & J. Kinnunen Scientific Reports volume 5, Article number: 9539 (2015)

Valleytronics can be realized by accessing different spins coupled with different valleys. In monolayer TMDs, time-reversal symmetry should be present while spatial symmetry should be broken to realize spin-valley polarization. People use a magnetic field to detect this spin-valley polarization. then why TRS is not broken on applying magnetic field?

Hi all, I am trying to do optical simulation of a simple structure comprising of Si and SiO2 in sdevice. Everything seems to work except for the fact that while visualizing the plots of parameters such as Optical Intensity, I am not seeing any raytracing in the oxide layers. Although light is propagating on to the subsequent silicon layer along the propagation direction, the oxide in between is not populated with the rays in SVisual plot, which is expected. Is there anything I should include in the code to turn on optical raytracing in the oxide ? Any help? Although Sentaurus is taking the right index and extinction values for oxide in the simulation. I checked it.

Without consulting the phase diagram (of still unexplored alloy systems) , how one can predict which alloying addition in an element would produce intermetallics with some given compositions? For example, how would one say that C is (one of the ) most crucial alloying element of Fe and Si of Al, with just consulting the periodic table and electronic structure? Of course, there is no objective definition of "most useful" alloy- the same alloying element raising strength would not be the one that raises ductility.

Some special properties can be reasoned as

I have just mentioned the two extremes of intermetallic formation and complete immiscibility- (complete miscibilities are well explained by hume-rothery rules, and ultimately also depends on how one objectively measures electronegativity), because there is, to my knowledge, no concrete rules to predict nature of phase diagram (isomorphous or eutectic or peritectic or monotectic or...) between two elements, let alone two compounds.

While electronic band structures of an element are available to be computed by standard methods, there is no systematic way to predict crystal structure or computed thermodynamic properties from composition alone (that are vastly generalizable).

I think there are scientific factors like cosmic and geological abundance, position in EMF series (and hence ease of extraction) as well as socioeconomic factors like market demand as choice for an alloying element. But is it possible to locate useful alloying elements for any of the elements with same unified rationale? (say of Mo, Ru, Rh, Pm, Tl)

And again, is there seemingly any way to tell which pair of metals or elements would be completely immiscible in solid states?

In theory, it is all about minimizing gibbs free energy, and from specific heat data of a solid, one can extract both values of enthalpy and entropy term. If this technique is generalizable for any solid, then why it is not used pervasively? is it because we just cannot predict the specific heat without crystal structure, and from chemistry alone, there is no way to predict crystal structure? Is it not possible to obtain Gibbs free energy of overlapping electron orbitals solely from schrodinger's equation, just like total energy is extracted from eigenvalues of Hamiltonian?

Hume-Rothery rules or Darken-Gurry maps are good starting points, but not good enough. Machine-learning based prediction can make things more systematic but without potentially answering the "why"s in a language familiar to humans . Interatomic potentials are scarce and very rarely generailizable for any group of elements (like Lennard-Jones for gases). My question finally boils down to- prediction of effect of alloying of any two elements, and ultimately composition to crystal structure and phase diagram calculation from first principle- is it even partially possible, if yes, how?

See some of my related questions

Thank you very very much to hold your patience to read the whole post :)

Hello everyone

Can you please clarify what is difference between field-effect mobility and Hall mobility? which one is more accurate to determine? are both equivalents?

(The image is taken from wikipedia https://en.wikipedia.org/wiki/Periodic_table_(crystal_structure) ,

and I claim no originality of creating the image)

The reason of the following structures are given in wikipedia, with some exceptions, at room temperature.

If all of these can be explained in terms of electronic configuration , then a significant electronic-to-crystal structure interrelation in simpler terms can be obtained.

(and possibly, ratio of metallic bandgap or Fermi energy etc. like energy parameters and average electron K.E at room temperature, then I think the correlation would be stronger. Perhaps, if one replaces spherical model of a metallic atom with its feasible 3D dirctional variation of outermost electron shell geometry, the the correlation is likely to be even stronger)

Generally we add spin-orbit interaction as a perturbation term in the system. which system has this spin-orbit term naturally in its hamiltonian.

A cif file represents a unit cell with minimum energy. My question is, in the start of any ab initio calculation for unit cell generated from the cif file, why we are advised to optimize cell parameters and atomic coordinates both. Can't we just optimize atomic coordinates or perform single point calculation?

While simulating the effect of a heavy ion strike on a reverse biased SiC Schottky diode in Sentaurus 3D, I see totally different maximum lattice temperatures when simulating different time ranges or even by selection of different number of points to be plotted in the same time range. Everything else including the device structure mesh etc remains the same.

The three solve statements below provide three different temperature profiles -

Solve {

            Poisson

            Coupled(Iterations= 100 LineSearchDamping= 1e-4){ Poisson Electron }

            Coupled(Iterations= 100 LineSearchDamping= 1e-4){ Poisson Electron Hole Temperature}

            NewCurrentPrefix= "Tr_"

            transient( InitialTime=0 Finaltime = 1e-8 increment=1.4

            InitialStep=1e-9 MaxStep=1e-8 MinStep=1e-25){

            coupled{ poisson electron hole Temperature}

            CurrentPlot ( Time= (Range= (0 1.0e-8) Intervals= 200))

    } 

}

Solve {

            Poisson

            Coupled(Iterations= 100 LineSearchDamping= 1e-4){ Poisson Electron }

            Coupled(Iterations= 100 LineSearchDamping= 1e-4){ Poisson Electron Hole Temperature}

            NewCurrentPrefix= "Tr_"

            transient( InitialTime=0 Finaltime = 1e-8 increment=1.4

            InitialStep=1e-9 MaxStep=1e-8 MinStep=1e-25){

            coupled{ poisson electron hole Temperature}

            CurrentPlot ( Time= (Range= (0 1.0e-8) Intervals= 2000))

     } 

}

Solve {

            Poisson

            Coupled(Iterations= 100 LineSearchDamping= 1e-4){ Poisson Electron }

            Coupled(Iterations= 100 LineSearchDamping= 1e-4){ Poisson Electron Hole Temperature}

            NewCurrentPrefix= "Tr_"

            transient( InitialTime=0 Finaltime = 1e-7 increment=1.4

            InitialStep=1e-9 MaxStep=1e-6 MinStep=1e-25)

            {

            coupled{ poisson electron hole Temperature}

            Plot ( Time= ( 1e-13; 5e-13; 1e-12; 5e-12; 6e-12; 1e-11; 1e-10; 1e-9; 1e-8; 1e-7) noOverwrite )

    } 

}

Would anybody have an idea of what could I be doing wrong ?

Any help to get the book titled Solid State Physics, Solid State Devices And Electronics. By C. M. Kachhava



Magnetic mirrors are well known in plasma physics. In order to work, the mean free path of the charge carriers has to be at least as long as the helical paths under the influence of the B field. Therefore, magnetic mirrors exert no mirror effect on the conduction electrons in metals under usual conditions. However, ultra-pure metals at low temperature provide a mean free path of several millimeters. If the mean free path becomes longer than the dimensions of the specimen, the conduction is called ballistic.

If a magnetic mirror had the same effect on a "ballistic electron gas" as on a plasma, different electron densities in front and at the back of the mirror would result, and hence a voltage across the mirror would appear. This voltage would be built up by using the thermal energy of the electrons. Obviously, a voltage source based on thermal energy (in the absense of a temperature gradient) violates the 2nd law of thermodynamics.

I have to admit that I do not deal with details of solid state physics on a daily basis, so this is some kind of doing "armchair physics". But I would very much like to recognize the flaw in my thinking, and I didn't find publications dealing explicitely with this topic. (Usually this means that the matter is so obvious that a publication wouldn't be worthwhile.) I wrote a short paper on this subject; the quantitative result is that one could expect an open circuit voltage of the order of 200 microvolts under feasible conditions:

Any helpful comments will be highly appreciated!

PS The magnetic flux density is assumed to be limited to about 1 T (Fermi energy = 11.1 eV (iron), B = 0.5 T => path diameter = 45 micrometer), so the magnetic field can be provided by permanent magnets. Since ballistic transport is limited to low temperature, an alternative would be the use of superconducting coils.

In a laboratory setup, the entropy of the whole system would be increased by the means for cooling the device. Assuming for the moment that the effect under consideration occurs at all, a battery of such voltage sources would however, after initial cooling, keep itself cool, provided that both the thermal insulation and the electric load, located outside the insulation, were sufficient.

Let's say we have a material AB. Is it possible to detect atomic clusters of A atoms experimentally?

The size of clusters in question: 2 atoms (nearest neighbour pairs), 3 atoms (nn triangles), 4 atoms (nn tetrahedrons).

Hello all,

I want to synthesize ZnO nanoparticles and PBABr in my lab for my LED project. I know the method, but I am not sure how can I check(even visually) that I have arrived at the correct result or prepared correct chemicals, If anyone could help me with that it would be great.

Thank you for being helpful with my other questions.

Jitesh

Every metal has its own work function. if several metals are used in multilayer structures such as [Co/Ni] multilayer what will be the effect of the work function of the electrode? Can these multilayer structures change the individual workfunction?

Hi,

I need HCI MOSRA simulation to find vth degradation. but I didn't know how to do it. especially I don't know what the constant parameters such as THCI0, TDCE, etc.

I use the following netlist to do the simulation, but the values of threshold voltage didn't change!

.model hci_1 mosra level=1

+thci0 = 5 tdce = 1 tdii = 2.7 hn = 0.5

.appendmodel hci_1 mosra nch nmos

.mosra relmode=1 reltotaltime='10*365*24*60*60' relstep='10*365*24*60*60/10'

+hcithreshold=0

+nbtithreshold=0

would you please help me with these problems?

I'm looking forward to receiving an email from you.

best regards,

Farzaneh Nakhaee

which is better for thin film growth, electron beam evaporation or sputtering?

which results in better film quality?

I have seen a number of publications state that organic radicals often exhibit quenched photo-luminescence, yet offer no explanation as to why. Can someone offer a physical explanation as to why this would be the case? This question is particularly puzzling to me as you can clearly see polaronic or excitonic absorption bands in an absorption spectrum corresponding to the excitation of the radical anion. Why then does it not luminesce when excited at these wavelengths?

Do we have a number for DOS (Nv, Nc) for 3D or 2D perovskites? Although I see few papers reporting DOS, I do not find a number. Or maybe I do not find a way to calculate DOS from the plots.

You can provide links with calculation and clear examples of the methods used. I would also like to understand how to take into account a specific potential. How to determine the forbidden zone for this case. And other useful things in determining the zone structure for this case.

Thank!

How to use Wigner-Seitz cell to calculate the nearest neighbor in a given crystal? What is the physical principal? And which (free) software can be used to do this calculation?

Like electronic density of states and bandstructure, we conclude bandgap, type of bandgap direct and indirect etc. Likewise what we conclude from phonon DOS ?

Any basic literature on phonon DOS and bandstructure analysis.

Any comment and conclusion on my phonon DOS plot which is attached here.

Thank You All

Shilendra

I am aware of many femtosecond laser based approaches to excite phonon modes e.g. in crystals and minerals. Quantum Cascade Lasers (QCLs) seem like an interesting alternative, especially since they can be tuned by frequency and can be operated continuously. Has someone tried to use QCLs to excite phonon modes? Or is there a catch?

We have setup the femtosecond Transient absorption system for nanowires or solution samples. Depending on the sample the pump may be 310 nm, 387 nm or 425 nm and similarly probe is be broadband white light continuum(350 nm-700 nm or 400 nm-750 nm. 

1. How do we know that our setup is working properly and we are getting right time constants? Is there any stable standard samples that we can use? 

2.Is the 1 arcsec retroreflector better option than using 2 mirrors in 4 ns delay stage ?

3. Please give me suggestions to improve my setup. I have attached the block diagram of my setup. 

I am currently reading some papers in the field of high Tc superconductivity. Some concepts confuse me. Can you tell me the definitions of spin wave, spin density wave, spin excitation, spin fluctuation, spin gap, charge density wave and charge order? What are the differences and correlations between these concepts? And, what their relationships with high Tc superconductivity?

Hi all, 

I am looking for a code or package to calculate density of state in metal (Mg alloy). Previously I used VASP but it is not reliable for high energy states. Also, I see many others using VASP to calculate lattice parameters and energy, but using another code to calculate density of states.

What will you do when you calculate DOS? What's the advantages compared with VASP?

Any suggestions will be appreciated.

Thanks in advanced!

I need information about reliability of BCS-Eliashberg-McMillan formalism especially for high Tc superconductors.

How is electron-phonon scattering treated in metals in the context of transport ? I believe that the conventional deformation potential theory used for semiconductors fails in case of metals due to the presence of multiple bands around Fermi level. Is a rigorous treatment using both electron and phonon bandstructure of metals the only way to do scattering in metals ? Or are there approximations that one can use (like deformation potential theory for semiconductors) ?

solid state physics, semiconductor, materials, chemistry, quantum wire, quantum physics, band gap, energy band diagram, opto-electronics, nano devices, heater structure, indirect and direct band gap.

CoronavirusCurrent trends in nanotechnology promise to make virus uses more diverse. From the point of view of materialists, viruses can be considered as nanoparticles. On its surface, viruses carry special tools designed to cross the host cell barriers. Viruses are commonly used in material science as scaffolds to contribute to associated surface modifications. There is a certain type of virus that can be designed from directed development. The powerful technologies developed by biology have become the basis of engineering methods toward nanomaterials, and have opened up wide areas of applications to biology and medicine. Because of their size and shape, as well as their specific chemical structures, viruses have been used as templates for organizing materials on the nanoscale. Recent examples include working at the Naval Research Laboratory in Washington, D.C., cowpea virus particles have been used to amplify signals in micro-DNA array sensors. In this application, the virus molecules separate the fluorescent pigments used to indicate blocking the formation of non-fluorescent diodes that act as dampers. Another example is the use of the cowpea virus as a nanoscale plate for molecular electronics. Is it possible for material science researchers to prepare nanocomposites that can interact with the Corona virus so that they can break down the virus into their primary compounds?

Hi, I am working on donor spectroscopy in Si. Due to low donor concentration around 10^16 cm-3, the PL signal I get by exciting 670 nm pump is very low, below noise floor. The system is locked-in already. Is there any other tricks you can share that you use for FTIR spectroscopy. I use Nicolet 8700 FTIR spectrometer with an external PL setup. The samples are in a cryostat and cooled with Liquid Helium.

I read in Ashcroft and Mermin's Solid State Physics how only those modes that have a frequency tending to 0 as k(or q) tends to 0 contribute to specific heat capacity. This would include the 3 acoustic modes and some exceptions of optical modes. Can someone please explain this to me.

i want to know, is it in the same way we use for a bulk system or not? If not, then what changes are required? what parameters do we look for?

It is claimed everywhere that PDMS can be bonded with silica-based materials, such as glass, quartz, and PDMS. I have successfully done PDMS-glass bonding with the following steps: 

1. Clean glass with Piranha and PDMS with acetone/IPA

2. Oxygen Plasma for 2min (50W)

3. Bond and cure for 15min at 90C oven

However, with the same recipe, I cannot bond PDMS with quartz. I believe the only difference is that quartz is 99% SiO2 while glass is less pure.

Is there any trick on bonding PDMS with quartz chip? 

As the explanation goes, hole is a figment to the absence of electron as it moves to some different energy state as a result of absorption of energy of some kind. That is, I think of holes as voids, which are "said to" have positive charge for the sake of charge neutrality because there once happened to be an electron at that place. But, it doesn't have it's own actual charge like any other physical charged particle (like an electron), right? Then, how can we define an exciton that is based on coulombic forces between an electron (in conduction band) and a hole (valence band), which actually requires presence of two physical charges?

If we have a new sample and we do not know its space group than how we can determine it's space group from xrd pattern (2theta vs intensity) .

I wish to do DFT calculations and use the frozen phonon approach via Phonopy. Should I pay attention to the magnetic moments?

Sometimes, individual atoms in a crystal have different magnetic moments. Does this have any additional effect?

For the transition from insulator to metal, there have different transition mechanisms.

How to distinguish Anderson transition (Anderson insulator was induced by the disorder-induced localization of electrons) from Mott transition (Mott insulator was induced by the Coulomb repulsion between electrons. This transition can be controlled by the mechanisms of  oxygen vacancy controlled electron filling), especially in 2 or 3-dimensions materials.

I need to calculate the barrier height of the Schottky contact based on thermionic emission theory, so i want to know the Richardson constant value for indium oxide.

To calculate the saturation current of the metal/ZnO/Si heterojunction diode which one should be considered for the Richardson constant. For example, whether we should consider the Richardson constant of ZnO or Si.