Questions tagged [density-functional-theory]

For questions about simulations using Density Functional Theory.

Filter by
Sorted by
Tagged with
9
votes
1answer
148 views

How to perform HSEsol in VASP calculations?

I want to perform HSEsol (PBEsol + HSE06) calculation on a material (monolayer) that doesn't have experimental data available. Could you please tell me how to ...
10
votes
1answer
179 views

A concern about IRC results

I've run an IRC (intrinsic reaction coordinates) calculation from my TS (transition state) and got two minima for each side. I am concerned about them. One of them took about 100 steps to be achieved ...
6
votes
0answers
22 views

Is it possible to calculate the variation of magnetization M(T) for a diluted magnetic semiconductor?

Is there any simulation program (for example a DFT package) to determine the variation of magnetization M(T) for dilute magnetic semiconductors or doped semiconductors with different concentrations of ...
9
votes
2answers
166 views

Can we consider SOC in FM materials using QE?

This is a follow-up question to my question posted here. I've been trying to study the effects of spin-orbit coupling (SOC) on the band structure of ferromagnetic (FM) material VSe$_{2}$. The input ...
11
votes
1answer
49 views

How can I properly attach ligands to a surface?

The main aim of my venture is to study the effect of the presence of surface ions on the band structure of Si slab using Quantum ESPRESSO. I've tried to use iQmol to attach ligands to the surface. The ...
5
votes
1answer
43 views

Fermi level shift downward in the thin film structure

I did a band structure calculation of a thin film structure with different number of atomic layers. I found that the original bulk gap was shifted upward and the Fermi level was shifted downward no ...
10
votes
1answer
272 views

How to make sure that my SCF calculation is correct?

hope you are doing well. I am trying to study the electronic properties of ZnO doped with transition metals (Co, Ni, Fe) using DFT calculation, I am a beginner on DFT calculation using quantum ...
12
votes
1answer
194 views

Structure relaxation of a thin film structure in VASP

I have some general questions about doing the structure relaxation of a thin film structure in VASP. I want to study the how the band structure evolves as we increase the number of layers of the ...
11
votes
1answer
104 views

Is there any relation between static correlation and finite-temperature smearing?

I am new to this field, so there is a chance that I am mixing two entirely different concepts together, but it seems to be that static correlation and finite-temperature smearing in DFT are somehow ...
5
votes
0answers
217 views

How to use hp.x in Quantum ESPRESSO to calculate Hubbard parameter [closed]

I want to work with GGA +U on Quantum espresso to calculate the electronic properties of Ni Co co-doped ZnO system, but I can't figure out how to use the hp.x program for my system to calculate the ...
8
votes
0answers
102 views

Band structure has unusual lines in the valence band using Quantum ESPRESSO

Currently, I am working on ZnO doped with nickel and cobalt. I performed the SCF, NCF, BANDS calculation and got the results, the calculation converges without any errors. After that I used BANDS.X to ...
12
votes
1answer
141 views

What is the best program to manipulate numerical DFT wavefunctions to calculate custom matrix elements?

For pedagogical reasons, I am looking for ways to calculate quantum-mechanical quantities such as $\langle m | \dot{m}\rangle, \langle m | \dot{n}\rangle, \langle m | \ddot{n}\rangle$ using ...
9
votes
1answer
104 views

Should I use a lower threshold for calculations involving SOC?

I'm studying a compound $\ce{VSe_2}$ using the DFT package Quantum ESPRESSO (QE). The following is the input file. ...
6
votes
1answer
86 views

What correlation effects are included in KS-DFT with LDA and GGA?

This post is inspired by this post: What correlation effects are included in DFT? The Kohn-Sham density functional theory (KS-DFT) are considered to be exact and can include all correlation effects in ...
5
votes
0answers
49 views

Is there a way I could calculate the pressure and use SOC at the same time?

I have been trying to find the appropriate k-point grid via convergence in quantum ESPRESSO (QE). The following is my input file. ...
7
votes
2answers
202 views

What is the meaning of the "PRIMCELL.vasp" file generated by VASPKIT tool during bandstructure inputs generation?

When I use VASPKIT tool to generate K-path KPOINTS file for Bandstructure calcualtion of a 4x4x1 supercell of a pure material, ...
11
votes
2answers
694 views

What's the relationship between the first HK theorem and the second HK theorem?

The first Hohenberg-Kohn (HK) theorem: The external potential $v(\vec{r})$ is determined, within a trivial additive constant, by the ground-state electron density $\rho(\vec{r})$. From basic quantum ...
10
votes
2answers
303 views

How to create a KPOINTS file (k-path) for 4x4x1 supercell bandstructure calculation?

How to generate or create the correct KPOINTS ( K-PATH) file for a 4x4x1 supercell bandstructure calculation ? Is there a software compatible with vasp can do that ?...
3
votes
1answer
53 views

Using double-hybrid functional instead of MP2 to avoid basis set dependence

I'm investigating reaction mechanism and I want to calculate energies of my reagents, products and TS on a higher level of theory than I use for the geometries and frequencies. I'm thinking about MP2, ...
4
votes
1answer
59 views

How to predict spin liquid materials with DFT?

In condensed matter physics, a quantum spin liquid is a phase of matter that can be formed by interacting quantum spins in certain magnetic materials. The novel concept has been realized in many ...
7
votes
0answers
304 views

Is there any code for local-orbital ab initio tight binding molecular dynamics other than fireball? [closed]

I was searching for a local-orbital ab-initio tight binding implementation of molecular dynamics and Ive found a code called fireball. Ive tried to compile it but the code seems to be buggy and there ...
5
votes
0answers
45 views

At what threshold would I assure convergence? [closed]

I'm a beginner in DFT and Im using quantum espreso. I've seen the difference of hydrostatic pressure being used as a criteria for converging my k-point grid and plane-wave cut-off values. I would like ...
12
votes
1answer
105 views

What are the physical consequences of adding a constant to the diagonal of the effective Hamiltonian of monolayer materials?

Effective Hamiltonians modeling many-layered materials are often tuned using some sort of bias voltage. For instance, in a $4\times 4$ Hamiltonian matrix to describe biased bilayer graphene using some ...
9
votes
1answer
358 views

How can I know if 3D aperiodic systems are not interacting with each other using Quantum ESPRESSO?

I wanted to observe the Projected Density of States of InP system passivated with Hydride ions. For that, the following input file was created. ...
5
votes
0answers
98 views

What is the relation between enthalpy, ionization potential, internal energy and HOMO/LUMO?

Is there any relation between enthalpy, ionization potential, internal energy and HOMO/LUMO? I am dehydrogenating a molecule and I need to study the enthalpy of dehydrogenation. If I get any relation ...
11
votes
1answer
262 views

Are different eigensolvers consistent within VASP (Algo=Normal vs Fast)

I tried to relax a 4x4x1 supercell of ferromagnetic monolayer material using the default settings (ALGO = Normal) but it didn't converge. So, I switched to ...
12
votes
2answers
162 views

About the surface Greens function method for calculating the surface state

Currently I'm using some software package to do the data analysis from the DFT calculation so that I can study the surface state of some topological insulator. I found that the method they use is ...
6
votes
0answers
40 views

Which energy should I consider while trying to analyse the variation in transport coefficients with temperature?

I am using the BolzTraP code [I'm completely new to this code] to calculate the thermo-electric coefficients as per this tutorial. And the output file obtained from BoltzTraP is given below. The ...
6
votes
0answers
55 views

Is it necessary to terminate the surface ions in a quantum dot?

I was trying to study quantum dots of ZnO. But I'm pretty new to creating and passivating 0-dimensional particles. Is it always necessary to passivate the free surface of the quantum dot? Regarding ...
14
votes
1answer
286 views

DFT Knowledge Check for Posed Problem

Currently I am trying to apply to a graduate program overseas. They require me to include a research proposal in my application. My topic of interest is computational materials science. So, one ...
8
votes
2answers
202 views

inconsistent behavior between band structure and density of states

I'm a beginner in DFT calculation. I have performed a DFT calculation on CuCoSnSe using PBE-GGA on Quantum Esspresso. When I plot the band structure and the total DOS, the band structure shows a ...
12
votes
0answers
95 views

What are the recent developments of GW@BSE to simulate the excited properties of materials?

A twin question related to the TDDFT method is asked in another post. But any comparisons between both methods in recent developments are welcome. The time-dependent density functional theory (TDDFT) ...
5
votes
0answers
38 views

Interpreting Critic2 charge analysis in metallic systems

I'm using Critic2 software to perform post-processing of the charge density of metallic alloys. With the charge density obtained from the Self-Consistent-Field calculation (for that I'm using Quantum ...
16
votes
0answers
119 views

What are the recent developments of TDDFT to simulate the excited properties of materials?

The time-dependent density functional theory (TDDFT) and the many-body perturbation method (GW@BSE) are considered as the two most popular and successful methods to describe the excited-stated ...
6
votes
0answers
82 views

Unresolvable inconsistency between charge and multiplicity and orbital occupancies. Error while Distance Scan [closed]

I get the message mentioned in the title after a distance scan with a Gaussian calculation. I have bound a gold atom to a carbon in the pyridine ring and now pull this further and further out with a ...
8
votes
0answers
58 views

Reaction mechanism elucidation methodology [closed]

I'm studying a mechanism of fluorine substitution in my molecule (the project isn't that much about actual research as learning computational chemistry). There are two $\ce{C6F5}$ rings and I want to ...
9
votes
1answer
106 views

Does the DOS plotted by p4vasp already have Fermi energy subtracted?

I have used both SUMO and P4VASP to generate a DOS plot. I have found that there's a shift (displacement) between the two DOS ...
11
votes
1answer
249 views

DFT optical calculation and plotting for real and imaginary permittivity in VASP?

I have calculated Frequency dependent optical permittivity of Au using (VASP) my INCAR tag includes LOPTICS=.TURE., my OUTCAR ...
13
votes
3answers
411 views

Ion-ion interaction potential in Kohn-Sham DFT

The Kohn-Sham equation as described in "Density Functional Theory: A Practical Introduction" by Dr David Sholl is: $$\tag{1}\left[-\frac{\hbar^2}{2m}\nabla^2+V({\bf r})+V_H({\bf r})+V_{XC}({\...
12
votes
1answer
190 views

How can I prove that a material is ferroelectric using DFT?

I would like to prove that a 2D material (Say ZnO) is ferroelectric. Since Ferroelectric materials are a subset of piezoelectric materials. How should I proceed to prove that the polarization is ...
17
votes
1answer
700 views

Deep Neural Networks: Are they able to provide insights for the many-electron problem or DFT?

The solution of the many-electron Schrodinger equation is the key to understand the properties of matter. However, it is notorious due to the exponential wall (for example, see section II (C) of ...
10
votes
1answer
143 views

Calculating/Visualizing electronic density from orbital information written in the Molden format

I'm trying to obtain an electron density from orbital information written in the Molden format by the formula, $$ \rho(\mathbf{r}) = \sum_{i}^{occ} |\phi_{i}(\mathbf{r})|^{2}. \tag{1} $$ Is there any ...
12
votes
2answers
382 views

Getting different total magnetic moment in 'scf' and 'vc-relax' calculations in Quantum ESPRESSO

I am performing a spin polarized DFT calculations in Quantum Espresso on a Co2MnSi ferromagnetic crystal. For this I have performed these steps: 1) Performed ...
8
votes
1answer
78 views

How to get correct ferroelectric polarization from a supercell calculation?

Although the ferroelectric polarization is usually calculated with primitive cell using the Berry phase method, supercells are sometimes needed for particular applications, e.g., defects, doping, etc. ...
7
votes
1answer
74 views

ISMEAR and SIGMA

I'm calculating the total energy at the ACFDT-RPA level using VASP in terms of this tutorial. For the first three steps it uses: ISMEAR = 0 ; SIGMA = 0.05 but for ...
12
votes
1answer
384 views

Are there any good books to learn how to use DFT+U?

I am interested in learning how to do DFT+U calculations and was wondering if anyone has any good recommendations for books or articles.
7
votes
0answers
116 views

The gap was open when I was doing an HSE + SOC DFT calculation

I used VASP as my DFT software to do a calculation on an anti-perovskite crystal. I try to reproduce the band structure from literature which was calculated based on HSE + SOC calculation. Their ...
8
votes
0answers
123 views

Can we calculate bond enthalpies for each bond in a supercell of a disordered AB crystal using DFT?

Apart from using Bader charge analysis or energy of formation estimation, I wonder if there is a way to compute the bond energy of constituent bonds in a crystal using density functional theory. Let's ...
8
votes
3answers
244 views

Does Kohn-Sham DFT use Slater determinants?

In the Hartree method, it is known that the wavefunction of the system does not obey the antisymmetry principle of fermions - that is when you swap two particles, they don't up a negative sign. ...
16
votes
2answers
421 views

What's the best way to compare two DFT codes?

What's the most efficient way to compare the two DFT codes in terms of computation time, basis sets (for example, one plane wave vs one atomic orbitals), functional performance, etc.?

1 2 3
4
5
11