Questions tagged [vasp]
For questions about use of the Vienna Ab initio Simulation Package (VASP).
266
questions
3
votes
0answers
32 views
The comparison of bandgap value of slab and bulk phase
I tried to calculate the bandgap of the TiO2-Rutile bulk phase, DFT(not +U) calculation shows the bandgap is about 1.8eV, which is roughly the same as the 1.78eV on the Material Project. When ...
5
votes
1answer
39 views
Fermi energy lower than valence band maximum?
I am trying to analyze the density of electronic states of a $\ce{TiO2}$ slab, but the result I got from VASP shows the fermi energy is lower than the valence band maximum (VBM) by a small energy ...
5
votes
0answers
37 views
Using pseudo-hydrogen results in semiconductor changing into a conductor [duplicate]
I tried to use pseudohydrogen to passivate the TiO2-Rutile(110)'s bottom side. As the following DOS diagram shows, pseudohydrogen does reduce the density of state near VBM and CBM, but it also causes ...
3
votes
0answers
10 views
Translate INCAR to Python script using ASE
I am considering using ASE to translate my old work into a Python script. I already have the INCAR and POSCAR KPOINTS files. Is it possible to let ASE read these files and generate Python scripts that ...
3
votes
0answers
22 views
Spin orbit coupling with HSE06
I tried to run a hybrid calculation (HSSE06) with SOC on VASP, I followed the steps in Jack's answer to HSE06+SOC method using VASP.
In step III (HSE06 SCF calculation with SOC (INCAR), should I be ...
4
votes
1answer
22 views
Using pseudo-hydrogen in VASP results in the wrong format in CONTCAR
I am using VASP to do the simulation of a slab, I used some pseudohydrogen to passivate the bottom side of the slab. After the structure optimization calculation, the ...
3
votes
0answers
19 views
Should I do the self-consistent calculation two times when using VASP 5.4.4?
According to the illustration on VASP wiki, there is a bug with VASP5.4.4, which would result in different charges for symmetrically equivalent atoms.
It seems this is an old bug confirmed by the VASP ...
6
votes
1answer
122 views
+100
Why don't we use the principal quantum number when building the projected density of state?
I am using VASP to calculate the projected DOS, but I am not sure why we aren't using the principal quantum number when doing the projection.
According to the VASP wiki, LORBIT would control VASP to ...
5
votes
1answer
34 views
The standard format and parser of VASP output files
I see a lot of post-processing tools for VASP, including ASE, VASPKIT,Pymagten and some other customized codes. They all read the VASP output files like a normal text file. Sometimes I would meet ...
5
votes
0answers
27 views
The workflow of VASP
I am trying to understand the workflow of VASP, so I make a simple diagram to show how VASP updates the related file during iteration. Did I make it right?
4
votes
0answers
22 views
How to get the right type of bandgap(indirect/direct) in VASP?
I am trying to calculate the band gap type(Direct or Indirect) of TiO2-Rutile, according to the Material Project, rutile is a direct bandgap type semiconductor. The VBM and CBM are both at the Gamma ...
4
votes
0answers
56 views
+50
How to set the AFM configuration in this doped monolayer system?
The figure below illustrates a 2x2x1 supercell of transition metal-doped CrI$_3$ monolayer. The red, green, and black atoms represent Cr, I, and transition metal atoms, respectively. I want to ...
7
votes
2answers
160 views
Does SCF calculation have to be done before calculating DOS?
The standard procedure to calculate DOS or band structure is:
Structure optimization,
SCF calculation,
non-SCF calculation.
According to the vasp wiki, it is because:
Mind: Since the charge density ...
4
votes
1answer
24 views
When should I use dipole correction?
I am trying to understand the function of dipole correction in DFT. I find that there are two examples related to this topic on the VASP wiki.
The first case is about CO on Ni 111 surface
The input ...
3
votes
1answer
23 views
How could I generate the parameter of 'selective dynamics' in POSCAR with ASE?
I often use selective dynamics to do structure optimization in VASP, but I am not sure how to do it when using ASE, it seems I could use the constraint class to tell ASE what I want to do.
My question ...
3
votes
1answer
18 views
How to keep the freedom of an atom along a specific direction in VASP?
I am trying to relax my model's structure by letting some atoms could move freely along some specific direction, in VASP, I could set selective dynamics, but it seems I could only adjust the freedom ...
5
votes
1answer
34 views
What is vaspcmd in job.sh of the official VASP examples?
There is job.sh script in a lot of official VASP examples, for example: Graphite MBD binding energy. it is used to help submit job on supercomputer
But in the script, it usually uses ...
7
votes
1answer
94 views
What is the principle of generating INCAR tags in ASE?
I am wondering if there is a detailed explanation about how ASE chooses the INCAR tags, since VASP already provides default values for a lot of tags, does ASE choose the default values?
There are a ...
8
votes
1answer
118 views
When to use pseudohydrogens to passivate a slab?
I often see some papers that don't use pseudohydrogen passivating the slab's bottom side when doing DFT simulation on the metal oxide's surface, for example, the following description is from a paper ...
11
votes
2answers
445 views
Why the band structure of a slab is not smooth?
I am trying to calculate the band structure of a TiO2-Rutile slab, but the result I got is not very smooth, and the result shows it is an indirect gap material, but the bulk phase of TiO2-Rutile is a ...
9
votes
1answer
56 views
How to improve a phonon spectrum calculation for a monolayer material?
I am a VASP user, and I would like to know what are the things to keep in mind to obtain a good phonons spectrum curve without imaginary frequencies in terms of:
Which method is better for monolayers?...
6
votes
0answers
34 views
How to solve this Phonopy-related problem?
I have used the finite displacements method for phonon spectrum calculation, and when I typed the command to create force sets:
...
4
votes
0answers
31 views
Berry Curvature with VASP+WANNIER90
I searched on the tutorials in WANNIER90 code and the example 18 says that the calculation of the berry curvature requires the recent version of pw2wannier90 interface. In other words, it requires the ...
6
votes
1answer
34 views
How to determine the right k-points for the band structure of a slab?
I am trying to compare the band structure of a slab and the bulk phase, just like the example on the VASP wiki. In the example of VASP, it calculates the band structure of the slab of Ni metal.
A slab ...
6
votes
2answers
47 views
DOSCAR file during structure relaxation is useless?
I am trying to figure out why the DOSCAR file during structure relation is useless, for the last step of structure, the atoms' positions are almost fixed, is that the same as a static calculation?
But ...
8
votes
1answer
95 views
What is the detailed difference between Vasp_std and Vasp_ncl?
I am trying to figure out the difference between vasp_std, vasp_gam, and vasp_ncl. I find some related details on the Vasp forum, I think vasp_gam makes some customized optimization for the gamma-...
6
votes
1answer
144 views
How to choose the best SIGMA value in VASP?
I am trying to test how to choose the SIGMA value in VASP, so I did a little bit of test.
Here is the input file:
INCAR
...
5
votes
0answers
62 views
What are the electronic steps and ionic steps in VASP?
I am getting confused about what the electronic step and ionic step are in VASP.
I used to think that finishing the following loop one time is called an electronic step. but I am not sure how to ...
6
votes
1answer
49 views
Is it necessary to do self-consistent calculation after structure optimization?
When calculating the band structure of a material, I have been told that at first, I need to do structure optimization to get a stationary structure(1st step), and then keep the atoms' position fixed, ...
6
votes
1answer
126 views
Why does it take 5-10 steps to obtain reasonable orbitals during initialization in VASP?
I am trying to figure out the initialization process of VASP, and I found an INCAR tag NELMDL, on the wiki page of NELMDL, it is said that VASP requires 5-10 steps to obtain the reasonable orbitals. ...
5
votes
1answer
57 views
Different between ENCUT and ENAUG in the VASP setting?
I am trying to figure out the difference between ENCUT and ENAUG in VASP settings, I found the following description on the wiki of VASP.
ENAUG specifies the cut-off energy of the plane wave ...
7
votes
1answer
35 views
Are CHARGE=2 and INIWAV=1 contradictory in the VASP setting?
When initializing the charge density in VASP, I set the parameters as follows:
...
8
votes
1answer
37 views
Does the INIWAV tag in VASP assume that the wavefunctions are plane waves?
I am trying to figure out how to set the initial wavefunction in VASP, on the VASP wiki page of INIWAV, it is said that VASP would fill wavefunction arrays with random numbers.
...
7
votes
1answer
50 views
Which IBRION tag should be used for finite displacement method in calculating Phonons spectrum?
I am planning to use the finite displacement method for calculating phonon spectrum, and I have prepared the INCAR file below to try it on a transition metal trihalide monolayer (e.g., VI$_3$). I ...
6
votes
0answers
64 views
How to interpret density of states and band structure of a material?
I am new on the VASP platform, and have learned how to calculate any material's DOS and Band structure.
However, I don't know how to interpret these properties. Can you recommend resources that ...
7
votes
2answers
74 views
How to determine the irreducible representation of an atomic orbital at a K point?
In this paper "Unified theory of direct or indirect band-gap nature of conventional semiconductors", the authors calculated the irreducible representations of atomic orbitals at three K ...
6
votes
1answer
48 views
Need INCAR equivalent Quantum Espresso input file
I am dealing with a magnetic system.
With Quantum Espresso I am getting the result as a half-metal but while using VASP we are getting it as a semiconductor.
I would be glad if someone can provide me ...
6
votes
1answer
47 views
Which one should be investigated first? dynamic stability or magnetic stability?
I would like to investigate the stability of $\ce{VI_3}$ monolayer, but I am confused about whether I start directly by performing Phonon spectrum calculation, or I should first investigate the ...
13
votes
1answer
124 views
Physical interpretation of k-points
What is the Physical interpretation of the k-points used in ab initio calculations? Why must the number of k-points be optimized rather than just using some large fixed number of them?
6
votes
1answer
127 views
How does electronic iteration work in a VASP relaxation calculation?
I am a beginner using VASP to do material modeling, and I'm confused about the following questions:
How does the electronic iteration work in VASP relaxation calculation?
Is the electronic iteration ...
7
votes
1answer
108 views
Unit Cell Parameters for VASP Calculations
For background, I have never used VASP before and have limited knowledge of how the software works. I am working on a program for the automation of structural creation for 2D materials. I am more of a ...
8
votes
1answer
267 views
Study of supercell after creating vacuum
For studying a bulk supercell, after creating some vacuum in it, I'm confused about how to relax it.
With VASP, I can do relaxation using NSW = 0 and ...
6
votes
2answers
88 views
Relation between lattice parameter and energy for relaxations
We have been wanting to do relaxation of lattice parameters as a function of the energy. I want to know the mathematical expression for this, and also the theoretical background related to this method....
8
votes
1answer
82 views
what do I need to change about typical VASP input file to calculate the energy of a single atom?
I'm a little confused how to make a VASP input file to calculate the energy for the isolated atom:
Do I need to change the lattice parameter of my unit cell or can keep the value for the whole system?...
6
votes
1answer
47 views
VASP Memory Estimate
Is there any way to get a memory estimate for VASP calculations either directly or indirectly (based on some example calculation)? For example, I would like to be able to predict based on my settings ...
5
votes
1answer
42 views
How to fix local magnetic moment of each ions in VASP?
In spin-polarized calculation,total magnetic moment can be fixed to a specific value using NUPDOWN tag. In non-colinear spin calculation, tag ...
4
votes
0answers
45 views
What are the challenges in using DFT to study the Hydrogen Evolution Reaction of (111), (110), (100) and (011) planes of Cobalt (III) Phosphide (CoP)
What are the challenges in using DFT (implemented in the VASP code) to study the hydrogen evolution reaction (HER) of the (111), (110), (100) and (011) surface planes of Cobalt (III) Phosphide CoP.
8
votes
1answer
63 views
How to choose a proper rotation matrix and apply it to rotate unit cell about Cartesian axis
In this paper, they have rotated the unit cell using a rotation matrix, so the axes are aligned with the atomic bonds. I would like to know how they calculated that rotation matrix, and which software ...
9
votes
1answer
76 views
In which conditions can the self-consistent Hubbard U value calculated using Quantum Espresso be used for other VASP calculations?
I have seen that some articles calculate Hubbard $U$ value self-consistently using Quantum Espresso code. Then, they use it in VASP calculations. My question is: In which conditions can this value be ...
3
votes
1answer
71 views
Job stops in between without showing any error
I am trying to calculate the dos of one bulk system. My dos calculation job stops in between without showing any error. Here I am attaching the link of my input dos calculation files. CONTCAR file is ...