Transition Metal - Science topic

Does Ni(II) ion bonded with "N" or "S" parts of the organic ligand?

Send me the paper related to this idea.

I have recently prepared transition metal chalcogenides using a selenization method (which involves evaporating a layer of metal film with an ion beam and then reacting it with selenium powder). However, the grown thin film exhibits a pronounced granular texture and numerous voids under an optical microscope. Despite having sharp Raman spectroscopy peaks, no photocurrent response from the material can be observed. May I ask what the reason for this is, and how should I regulate the growth of the thin film? (What should be used as the criterion for evaluating the quality of the thin film? Must the quality of thin films prepared by this method be inferior to those prepared by chemical vapor deposition?)

I need a Protein Database File and a topology file for simulation

Why is mercury metal, unlike all transition metals, liquid? How to explain this scientific fact to students in simple language?

Dear Prof/Researcher/scientist's,

Generally, Energy and power densities are calculated from the device, (or/but), some reported paper's calculated from the three-electrode system.

Please kindly reply researcher's and professor's

2. Another question : How to mass balance (m- = m+) for Asymmetric supercapacitor?,

Cathode: transition Metal oxide (ex: NiO) and Anode A.C

How to charge balance (Q- = Q+), Please kindly give the reply (hand written/ or reference)

Hello everyone,

I am a chemistry student working on my graduation project focusing on transition metal acetylacetonate complexes, specifically Fe, Mn, and Cu. I am looking for the best solvents to use for preparing solutions for electrical conductivity (EC) and UV measurements.

If anyone has experience or suggestions regarding suitable solvents or any tips on preparing these solutions, I would greatly appreciate your input!

Thank you in advance!

Generally hybrid functions in the DFT modelling description electron-electron and electron-nuclei well. Do they can also describe the strongly corrected electrons systems, e.g. 3d transition metal oxides and van der Waals interactions between molecules ?

I am using Materials Studio and the CASTEP software package. I would like to apply Hubbard U corrections to a model that includes transition metals. Should I directly adjust the Hubbard U values for the atoms in the "Electronic Configuration" section, and do I need to enable the LDA+U option during the calculations?

If I don't use LDA+U, will the system be unable to recognize the Hubbard U correction values?

Palladium seems to coordinated to strong with a N-Boc amino acid in my substrate. What kind of transition metal has minor coordination with N-Boc amino acid? Is there any references?

Only the absorption side is considered, and the fine structure of the extended side is not considered

I have been working on sesqui-chalcogenides, i.e., M2X3 structure where M=transition metal and X=chalcogen with VASP. After simulating the bandstructure for both the non spin-polarised and spin-polarized case, I found two different bandgaps that are far different. I tried to reproduce the data on Nb2Se3 and found the bandstructure and Density of States to be the similar. hence I hope my results are accurate. Only problem is I got a negetive value (-2.9 eV) for ISPIN=1 and 0.007 for ISPIN=2 and their TDOS is also different. I have attached the plots here.

Bandgap and TDOS are solely dependent on the crystal structure and material itself, aren't they? Then why do I get different results? Which one is accurate,polarised or non-polarized case? The situation really gets worse, as a negative bandgap might be an indication of topological insulation (band inversion). How do I know if the band is really inverted and it is topological insulator or it is metal and the negative value is due to the underestimation of bandgap by LDA and GGA?

when we analyse the bond type between the transition metal atom and nonmetal atoms, for instance, B or N, it will arouse a problem bothering me. which chemical bonding type will form, covalent or ionic or other? how should we confirm it use the proper method?

Dear all,

In specialized literature, it is usually reported that asymmetry due to the conduction band accepting electrons from shake-up processes after the ejection of the initial core electron becomes more significant for transition metals when the cluster size decreases. However, there are also numerous examples in the literature where symmetric line shapes (G/L) have been used to fit the M(0) component of metal nanoparticles, especially when the spectral resolution is low.

On the other hand, for metal carbides, I found people tend to use asymmetric line shapes when the crystallite size of the carbide becomes larger than 2-3 nm.

In summary:

1) I was wondering how critical it is to consider the asymmetry in transition metal NPs when acquiring low-resolution XPS spectra. Is the asymmetry affected by the pass energy and the fact of having low metal loadings?

2) Is there a reliable method for predicting the degree of asymmetry, apart from using standards that replicate a transition metal nanoparticle in a complete zero-valent state in an analogous environment?

3) Are there truly general rules for predicting how asymmetry changes with cluster size in metal and metal carbides particles?

When I refined my XRD data by using GSAS software, the GOF value always came out at more than 4. My material is an O3-type layered transition metal oxide cathode material.

I'm currently working on the PMS activation so I wonder about the difference between using MOF, metal oxide, or metal hydroxide as a heterogeneous catalyst, and what are the better ones. I'm looking forward to your answer. I truly appreciate your helping.

can anyone give me advise about charge transfer transition of transition metal and rare earth element?

and usually people see the FL and absorption, emission spectra of those materials in glass, and I just want to know how much energy need to ionization the transition metal and rare earth element.

Could you recommend some studying source about it?

Transition Metal Catalysis.

I have been pondering why nickel only exists as the Ni2+ ion in nature. I know that Ni+ and Ni3+ also exist, but unlike iron (Fe), Ni3+ is not nearly as common as Ni2+. So, I have investigated this and arrived at an explanation but haven't quite reached a conclusion yet.

This is how I understand it:

Nickel has an electron configuration of (Ar)4s2_3d8, and iron has (Ar)4s2_3d6.

It's easy to understand the ionization to Fe2+ and Ni2+ because the 4s2 electrons are farther from the nucleus and now easier to remove. It's also easy to comprehend that the ionization energy is higher for iron because the 3d shell in nickel has more electrons, thus shielding more against the nucleus's attractive force.

Ionizing to Fe3+ might be understandable as it might be relatively easy to remove one of iron's only paired electrons in 3d6, and I guess that 3d5 is stable because the shell is half-filled.

But why is it so challenging to ionize nickel's 3d8 to 3d7, 3d6, etc.? Is a shell with 8 electrons already stable? Or why is it so?

I hope to be able to understand this.

I have been trying to get reasonably accurate values for oxidation states and ionic radii for ions in transition metal sulfide materials from their VASP outputs. I tried using the bader charge analysis code on the CHGCAR file (by summing up AECCAR0 and AECCAR2 files). The ionic radii calculated from the atomic volumes given in the AVF.dat file is not giving the radii values as expected (Au+ is larger than S2- according to the analysis). Also, kindly suggest how can I determine the oxidation states of the metal ions from the bader charges on each atom.

I have used the equal amount of same salt of two different metal like CuCl2 and ZnCl2, Oxidation of both metal is same but XRD peaks of only one metal has appeared. Even that both metal have their XRD peaks at different angles. If un-equal amount is used then one metal has broad peaks while 2nd metal is has minor peaks. Please guide.

Hello.

I am doing some DFT calculations on transition metal carbide; zirconium carbide.

There already exists some ZrC DFT papers.

However I can't find any reference that indicated Hubbard u parameter.

So is it okay to exclude Hubbard U parameter for ZrC?

Thanks.

Is it possible that a semiconductor when doped with transition metal may have its resistivity in the MegaOhm-cm range? The resistivity of the material without doping is however between 0.9 - 1 Ohm-cm.

I am doing VASP calculations with a bulk triclinic lattice system involving transition metals Cr and V. I know that you can check the spin for the entire system with the OSZICAR file from VASP but is there a way to check the spin multiplicity on each individual V atom and each individual Cr atom in the system to see how many unpaired spins each transition metal atom has?

I have tried various transition metal catalysts of Zn/Cu/Al/Fe/ as Lewis acids, but no product.

I am working on transition metal oxides, an antiferromagnetic system. I trying to calculate the activation barrier and transition state of the system. I am using Nudged Elastic Band method implemented in the program Quantum Espresso. Unfortunately, the NEB calculation is not converging. I tried lowering the mixing_beta value and tried adding an intermediate image, but still, it was not converging.

The magnetization values in the reactant and product are different. However, since we cannot specify different starting magnetizations for the reactant and product in the NEB calculation, we have used the same values for both the reactant and the product. I would like to know whether our approach is correct and also would like to know what can be done to achieve convergence of the NEB calculation of such magnetically ordered systems.

During the transport of oxygen Fe and Cu plays a vital role but why not other transition metals like Co, Mn, and others, what is the reason behind this?

I use the material studio software to research water splitting by a single transition metal electrocatalyst.

It's as a simple or complicated question as follows. After we published 2001 a certain article in Electrochimica Acta (https://doi.org/10.1016/S0013-4686(01)00738-1), where we showed in our recent article (10.1016/j.electacta.2023.142458) that the charge storage process in oxides containing transition metals (TMOs) could be a physical process without restrictions due to mass transport, now with new "insights", we publish this article below where a new theoretical model for TMOs yields different equations contemplating the different electrochemical techniques (e.g., voltammetry, chrono-methods, and impedance). It was demonstrated, comparing with renowned works (e.g., Trasatti et al. - more than 1100 citations and De Levie - more than 1400 citations) that in the specific case of TMOs, widely used in Energy Storage Devices, that the proposed model in this our work allows a "complete interpretation" of the main phenomena occurring during the charge/discharge process in Supercapacitors. On the contrary, the famous models of Trasatti and De Levie completely fail in the light of the present work.

We also validated the proposed model in carbon-based materials such as Activated Carbon and Pressed Nanotubes. See our work below using Chronocoulometry and Chronoamperometry, respectively:

(Lenon et al.) https://doi.org/10.1016/j.jelechem.2022.117140

(Pinzón et al.) https://doi.org/10.1016/j.est.2023.106858

Link for free access from the Publisher valid for 50 days:

In addition to the published paper, I am feeling the necessity to clarify some points not considered explicitly by us of historical relevance and important consequences as is the misinterpretations of the charge-storage process in Pseudocapacitors committed by several authors. The history behind the attempt to explain the theoretical basis of the pseudocapacitance in TMO (or DSA) electrode materials has two major authors, Professor S. Trasatti and Professor B.E. Conway. To quote, Trasatti (Italy) and Conway (Canada) were two of the greatest Electrochemists of the phase called “Modern Electrochemistry” together with Delahay, Sluyters, Vetter, Parsons, Savèant, Oldham, De Levie, Lasia, Bockris, Bard, among others. However, Professor Trasatti, who proposed the Protonic Condenser model for TMOs, always insisted on an intuitive (ad hoc) method of analysis. In this way, he and his co-workers completely failed to obtain significant “quantitative simulations” for the dependence of voltammetric charge as a function of the scan rate (CV technique) by using the equation q = a + b/[root(scan rate)] and/or 1/q = c + d[root(scan rate)], that is, Trasatti et al. used the charge referring to cyclic voltammetry, even knowing that there is no way to perform the analytical integration of the Randles-Sevckic model to obtain the theoretical charge-scan rate dependency for reversible systems. The use by several authors of this model proposed in 1989 led to numerous errors in the literature. The largest of these errors culminates in the model commonly known as Dunn’s model which is used to decouple the capacitive charge contribution and its faradaic counterpart controlled by diffusion mass-transport. These last authors committed the gross error of assuming that the slope in your equation, i-total/(scan rate root) = (ic)x(scan rate root) + (if), does not vary with the electrode potential, which is impossible according to the CV theory, i.e., the so-called “current function – Xsi(pi-time)” varies for each potential/voltage value. In the case of Professor Conway’s works dealing with pseudocapacitors, he tried to explain using the impedance technique (EIS) by applying "non-blocked" equivalent circuits composed of two distinct time constants (see the models in his classic book on SCs) to include in an "ad hoc" way his classical models developed between 1960-1970 related to "pseudocapacitance adsorption" using the CV technique. Then, using the so-called "brush model", he unsuccessfully tried to explain the phenomena of an electrical double layer linked to surface roughness with cyclic voltammetry using a single time constant. On the contrary, between 2014-2017, Saveànt et al. published important articles where they proposed that capacitance and pseudocapacitance are equivalent (indistinguishable) events. However, these authors were not concerned with the "roughness/porosity” factors, thus leaving behind the aspects related to the resistances and capacitances distributed into pores/cracks. Bearing all this short history in mind, our present article published in April 2023 innovatively addressed the fundamental aspects of pseudocapacitors that were not properly, intentionally, or not, considered by several prominent authors. Finally, our article tried to unify using a simplified model the use of the different electrochemical techniques in light of a single theoretical premise. It is worth mentioning that Professor A. Lasia previously considered some fails in De Levie’s model, when applied to real electrodes containing an assembly of pores, by including the capacitance referring to the flat regions connecting the individual pores as a parallel combination (Ctotal = Cporous + Cflat). This is necessary since De Levie proposed analytical solutions for single pores.

I plan to design a coprecipitation experiment with multiple transition metal ions (Mn2+, Fe2+, Ni2+) coprecipitated by NaOH, I want to design a more rational experiment so that these transition metal ions could precipitate simultateously at atom-scale mixing. I spent a long time searching that online but failed to find the solubility product constants of materials at different temperature, only end up with a table listing solubility product constants of materials at 25 ^oC. I will be very grateful if you can recommend a book containing solubility product constants of different materials at different temperature. Thank you.

Can the electrochemical reactivity of gases such as O2, CO2, N2 and transition metal phthalocyanines change in distilled water or phosphate buffer (pH 7)?

When a saturated solution of each gas was reacted with a metal phthalocyanine-coated carbon electrode in each solvent, the appearance of peaks changed between PBS and distilled water.

Are there any effects of solvents?

I would like you to teach me about that. Thank you.

Concerning MXene's structural types, I'm getting stuck. According to my knowledge, the MXene structure is classified into three categories: mono transition metal, double transition metal, and divacancy transition metal.

So, I want to know whether divacancy transition mxene is considered a sort of double transition metal or a distinct subtype of mxene.

Do "in-order" and "out-order" MXene fall under the category of Double Transition Metal MXene or Divacancy MXene?

When we dope ZnO with Co or Fe or Ni its band gap mostly decreases, but sometimes it increases with it. What's the reason behind it?

I try to compute the orbital energies of transition metals with ORCA. However, the output files (produced by Avogadro) allways contain only the highest occupied orbital energies (HOMO-8 and upwards) and many more unoccupied orbitals. How do I compute all occupied orbitals down to core level?

Hello everyone. please help me

I want to know why titanium nitride(TiN) has better electrical conductivity than titanium oxide(TiO2).

Thesedays, i did some experiments about PEMFC bipolar plate.

I installed TiN coating to titanium substrate. And, interfacial contact resistance was improved.

But. I dont know why transition metal nitride (CrN, TiN etc) has good electrical conductivity.

I desire to be able to identify the position of M-N and M-O functional groups in a complex compound from an FT-IR Spectroscopy

Dear RG community

I wonder if you could help me with a technical issue related to the activation of the methyliden =CH2 present at the isopropenyl moiety in cannabidiol molecule, so that C atom could be used as a potential ligand in a reaction with a transition metal salt as Fe, Cu, Co or V.

Could you please help me with a synthetic pathway or with scientific literature related to this kind of transformations?

In attention to your valuable answers, thank you.

To the best of our knowledge, 13 among 203 catalysts have overcome the peak power density (PPD) threshold of 1000 mW.cm-2 , which belong to the four categories i.e. Metal-Nitrogen-Carbon (M-N-C), BimetalsNitrogen-Carbon (MM-N-C), Transition metal oxides (TMO), and non-metallic catalysts (NMC). The improvement in catalyst’s porosity, surface area, conjugation of active sites, and thereby the synthesis procedures have a great effect on the ORR activity and fuel cell performance.

EXAFS is a spectroscopic technique used to investigate the structure of materials at the atomic level. It is particularly useful for studying coordination environments of transition metal atoms. EXAFS can be used to study a wide range of materials, including metals, alloys, intermetallic compounds, metal oxides, and metal-organic frameworks.

How to do sulfidation of 2D transition metals with sulfur powder?

I'm working on a DFT study of the catalytic properties of transition-metal-ion-doped crystalline cellulose coating in a gas reaction. I modeled it using a complex of a cellobiose and a metal ion with the reactant gas at the pre-reaction complex. But, my supervisor said that my model was too far from the real condition and did not meaningful as the solid coating was modeled in the gas phase. How to make a better one? Do you have any literature about it? Thanks

To change the optical properties of a structure, I intend to use doping it with transition metals. On what basis do you think I should choose these metals? For example, if I chose Mn, what should I say about the reason for my choice?

Hello my friends,

I synthesized Li-rich cathode materials with different transition metal: citric acid ratios.

my question

Why does the I(003)/I(104) ratio rise as the transition metal: citric acid ratio rises? What is the ideal ratio of I (003) to I (104)?

is there any software or methods to identifying bonding~functional groups of Raman spectra

By definition MAX Phases are Hexagonal layered transition metal carbides and nitrides. The question is while etching MAX Phases does the Hexagonal crystal system gets disturbed to an another crystal system or remain the same? I need answer form XRD Point of view

metal carbide and nitride specly 4 5 6 group transition metal carbides and nitride.

Is rast camphor method is sufficient

Hi all, I came across various sources of articles that discuss the activation of PMS and PDS via the use of transition metals as listed below. While some sources suggest that PMS is better while others suggest that PDS is better. I have a few questions for those that have tried these methods of activation below. I am relatively new to this form of AOP, so do excuse my ignorance.

1) Are reduced metals (ie Fe2+) better than their oxidised counterparts (Fe3+)? some articles do suggest the use of ferric ions as activators

2) what are some of the differences in terms of selectivity for the oxidation pathway of PDS vs PMS. While the review article did discuss some key factors "PMS is more effectively activated to yield SO4•– by transition metals (e.g., Co(II), CuFe2O4, Fe2O3) than PDS due to the unsymmetrical molecular structure' I would like to know if anyone did a direct comparison for such a case and are there documented papers on this?

3) Am I am able to perform this combination PMS+oxdidised form of transition metals or PDS+oxidised form of transition metals? (since there are conflicting literature that suggest that oxidsed form of activation is still possible, where most literature report only the reduced form)

4) Are there any oxidation byproducts that are of particular concern when using PMS/PDS?

Hello dears,

Why in the perovskite family (BaTiO3+-), we found always a partial substitution by Fe in the site B not other transition metals like Co etc., this is can be related to the size of atoms or only related to the oxidation state of the metal?

Thanks and best regards

INES

Hello,

Au does not form a good metal-oxide interface, we obviously need to insert an adhesion metal layer (Cr, Ti, etc) to make a good bonding with the substrate. I was wondering if there is any way to improve the adhesion between gold and a transition metal oxide film (SrTiO3 thin film) without an extra adhesion layer. Would thermal annealing be helpful? Or plasma cleaning of SrTiO3 surface right before Au deposition? I use electron beam evaporator for Au deposition (~30nm).

I would greatly appreciate any suggestion!

Novel 2D MBenes: 2D transition metal borides are the very promising catalyst for electrochemical ammonia NH3 synthesis

I would like to know the oxidation state of a transition metal oxide nanoparticle, what is a good choice of substrate for that purpose?

The molecules contain Fe, B,C,H, F. The scf energies are very close to converging but they just don't converge. I tried increasing the scf cycles, changing the input geometry etc. I am using the basis set of def2tzvpd.

So far, I have made and published about 20 complexes of the Schiff Base diiminopyridine Ligands and transition metal. I am now looking to collaborate so that we can write a review article about these structures. I have 20 relevant safe files

Hello, I am interested to study the diffusion coefficient of the flow of the transition metals through Ar gas using Molecular Dynamics. I would like to know which software is more suitable for this modeling? Thank you in advance.

I am trying to assess the potential for a set of small molecules to bind to transition metals (Cu2+, Zn2+, Fe2+, etc.), and am wondering if there is an established protocol for assessing binding constants.

One of the closer examples I have is the following paper (https://pubs.rsc.org/en/content/articlepdf/2006/cc/b611031b), in which the researchers test the absorbance spectra of a small molecule probe against ATP using a standard spectrophotometer. Would I then construct a concentration-response curve from a selected wavelength that shifts with a titration of metal?

I appreciate any and all help! Why is it that Beer's Law is popping in my head?

I have used the linear responce method to calculate Hubbard's U in VASP as indicated by VASP tutorals in their website. I give the url:

However my system is a zeolite and the transition metals I work with are not located in equivalent locations. One that has worked with zeolites knows that we identify various sites when we are are talking about metals in zeolites.

What I have not found in the bibliography and seems intimidating is to work with, is implementation of different values of U for the same kind of atoms in the system.

I'm trying to figure out the origin shake up satellite features that are seen in transition metal oxides. From what I understand the shake up features originate when the ejected core electron excites a valance electron and the KE of of the core electron reduces as a result of the excitation. I found the following in "Core Level Spectroscopy" by DeGroot; "The satellite was first considered to be caused by the shake-up transition between the metal 3d and 4s orbitals, but it is now well established that it originates from the charge transfer between the ligand 2p and metal 3d orbitals. I'm a bit confused on connecting the definition of a shake-up feature with what is said by DeGroot. Does it mean the electrons that are shared by the ligand 2p and 3d gets excited by the ejected core electron that give rise to the shake-up satellite? And can we assume that one reason to see shake-up satellite peaks in 3p energy range are the shared electrons between 3p and 3d orbitals?

Thanks in advance!

While I understand the core electron binding energy of an element (XPS), e.g. Cr, will increase if some of its valance electrons participate in bonding formation, however, I am not sure about the followings:

(1) Whether there is any correlation between core electron binding energy and bond strength, say for a certain type of bond, the higher core electron binding energy indicates stronger bond and vice versa? Or, no such correlation? For example, in transition metal carbides or nitrides, Cr23C6, CrN etc.

(2) Or, is the electron binding energy only impacted by the number of valence electrons participating in bonding formation (outer shell electrons deviating from the nucleus, thus the nucleus will have a higher attraction towards the core electron)?

Aside questions:

(1) What're the experimental methods of evaluating a bond strength or bond energy, say, between Cr and nitrogen in different species of chromium nitrides?

(2) Is the bonding energy the same as the bond dissociation energy? Can the bond strength (energy) be presumably induced from the melting points or hardness values of compounds, e.g carbides and nitrides?

Thanks!

Zhe

I’m looking for software that can predict kinetics of transition metals oxidation at low temperatures.

I intend to calculate the transition state energies for methane pyrolysis reaction over a transition metal (catalyst) using Quantum Espresso for the DFT calculations. I am looking for any comprehensive resource that could help me in this task. Kindly help out with a suggestion or two. Thanks

Dear RG,

I want to work on a metal complex consisting of two transition metals and a bridging ligand maybe Phenanthroline. I will be very happy if RG will help me with links, materials, and video/lectures to carry on this research.

Thank you in advance.

What are the transition metal dopants that can be used for a QDSSC? What are the quality to select a transition metal dopant in QDSSC?

Hello everyone!

I am looking for a way to analyze the interaction of a gas with the adsorption site of a solid.

SAPT seems very attractive for non-covalent interactions but when the adsorption site contains a transition metal, covalent phenomena may occur.

So is there any reliable method that can account for covalent bonding?

Oxygen oxidation is very essential at high voltage (>4.5 V) to improve the charge/discharge capacity in Li-rich cathode batteries. By oxyanion oxidation, oxygen release will happen and Li+ and O2- vacancies are occupied by transition metals especially Mn2+, which decrease the Li+ ion diffusion back.

I need to suppress the oxygen release in Li-rich cathode oxide. How can I do to increase the M-O binding energy to decrease the oxygen release?

Thanks

What is so special about metallic Pd that it can absorb around 900 times its own volumes of hydrogen? I was searching articles, but I couldn't find an answer to this question. All researchers say that Pd is called a "hydrogen sponge", it forms alpha and beta-hydride depending on hydrogen pressure and concentration, that PdHx is a p-type semiconductor, alloying Ag and Pd could further increase the hydrogen absorption, etc. It is a statement of facts rather than an explanation. Other transition metals also form hydrides - Pt, Ni, Ag, etc. But what makes Pd so special? Maybe this happens due to Pd's electronic configuration, or its crystal lattice, electron affinity, or a combination of different factors?

I am looking forward to synthesis various hexacyanometallates, hexacyano -manganates, -cobaltates and -chromates in particular. What would be the options? I have hexacyanoferrates, but do not have sodium/potassium cyanides, and there is no option of purchasing any cyanide salt.

Whould you please, suggest, if it is possible, other way of sythesising Prussian blue salts with various transition metals.

Thanks!

Metal oxide nanoparticles are being used as nanofertilizers. Which one is effective in transition metal oxides?

Dear colleagues,

I am studying half-metal ferromagnetic bulk material. So by definition half-metal means presence of a band-gap for minority (spin-down) states. Both VASP and Quantum espresso (plane-wave DFT packages) reproduce perfectly half-metallic DOS with a band-gap at the Fermi level (E-Ef = 0 eV).

While in the case of Siesta the DOS shape is nicely preserved BUT it's systematically shifted to the right at ~ 0.5 eV. As a result, no band gap at the Efermi, see the figure attached.

Shortly it means that Siesta doesn't allow to consider my bulk as half-metal in contrast to e.g. VASP and QE.

Maybe it's some technical artefact (some equation in the Siesta code) cased by half-metallicity and, therefore, wrong evaluation of equilibrium Fermi level when spin-up states are presented and spin-down are not.

Maybe the reason is that VASP and QE are plane-wave packages while Siesta employs atomic orbitals as a basis set. But can it explain my problem?

- Use LDA/GGA and other functionals

- Change k-points/cutoff

- Change basis (SZP, DZP, etc.)

- Implement +U (for the transition metal Co and Fe atoms but it only broadens Eg to the right)

- Change smearing

In all these cases Siesta DOS is shifted ~0.5 eV to the right in comparison with VASP & QE. And I have no idea what to do...

I would highly appreciate any suggestions or advices. Thank you!

Hi folks,

Currently running some convergence tests for magneto-crystalline anisotropy energy (MAE) of Fe (e.g. E_111 vs E_110 vs E_001).

As you know calculating MAE requires very strict convergence criteria as the relative energies can be on the order of 1 µeV, and can require k-points on the order of 10,000 or more.

However, the calculation is also dependent on the smearing width, which has a non-negligible influence on the # of k-points required for convergence, and smaller smearing requires higher k-points.

I am currently using VASP with the tetrahedron method with Blöchl corrections (ISMEAR = -5), with 0.01 eV smearing, and I find that 10k k-points is not enough to reach convergance (it has reached only ~ <2 ueV).

Before continuing with a higher k-point density I would like to get some input if 0.01 eV is appropriate, or if raising the value to 0.1 eV, while it may help convergance at smaller k-point mesh size, would impact the accuracy of the MAE energy? At 0.01 eV smearing and 10-kpoints, the relative anisotropy E_111 > E_110 > E_001 of Fe is correctly predicted, but I don't know how accurate the magnitude would change with smearing, or if perhaps I should try even smaller smearing widths.

Thanks in advance,

-B

Any suggestions on selection of suitable insulating substrate, matching lattice parameters for graphene synthesis, as an alternative to usual transition metal substrates (e.g., copper, nickel etc.).

My interest is the magnetic properties of these systems, using ORCA software under Linux environment.

thank for all.