5
votes
Accepted
The Appearance of Imaginary Frequencies in Lattice Vibration Calculations with Increasing KPOINTS
In the usual perturbation theory approach, we optimise a structure to minimise the forces (to zero, within some small tolerance) and obtain the ground state structure (or a local energy minimum). ...
- 6,647
5
votes
Accepted
How can I perform a cell shape relaxation in a specified direction using VASP?
As of July 2023 at least, VASP doesn't have such a functionality (see this post). I know of two options (I've used the first one frequently when relaxing slab structures while keeping the vacuum axis ...
- 1,099
4
votes
Accepted
Optimal choice between ISIF = 3 and ISIF = 4 for lattice parameter and atomic position relaxation in VASP calculations
You've already summarized the differences in your question, but to be complete: ISIF=3 has an additional degree of freedom that allows the cell volume to change. In principle, there should be no ...
- 176
4
votes
Fitting of Brich-Murnaghan equation of state
If you know Julia, I have a package called EquationsOfStateOfSolids.jl that is designed to do this.
It currently can fit and evaluate $E(V)$, $P(V)$, and $B(V)$ on several equations of state:
...
- 176
4
votes
Accepted
Can the the relaxed energy of a material system (eV/atom) computed by DFT using VASP be positive?
When DFT is being used for electronic structure energy calculations, a negative energy would be indicative of bound electrons. There's nothing physically, chemically or mathematically illegal about ...
- 33.6k
4
votes
Can the the relaxed energy of a material system (eV/atom) computed by DFT using VASP be positive?
Firstly, by expressing the energy per atom (eV/atom), it allows for a more convenient comparison between different materials or systems, as it provides a measure of the energy on a per-atom basis. ...
- 965
3
votes
Accepted
Random velocity generation
You can use ASE to generate the required random velocities, you may refer to this sample code to achieve this taks:
...
- 965
3
votes
Adsorption of Li on GeC (optimization problem)
The adsorption energy of Li or K atoms on a GeC sheet is influenced by several factors, including the electronic structure, bonding interactions, and surface reactivity of the materials involved. If ...
- 965
3
votes
Fitting of Brich-Murnaghan equation of state
Here are some references from my own work:
a script that reads energy-volume data from a csv file and fits a Vinet equation of state: https://github.com/flokno/tools.mlff/blob/main/mlfftools/scripts/...
- 136
2
votes
Calculation of charge defect formation energy
First, the energy correction term, $E_{corr}$.
It arises due to presence of periodic boundary conditions (defects are spuriously repeated) and of background charge compensation (hidden from the user). ...
- 61
2
votes
How to define a mesoporous material in VASP (introducing the vacuum gap)
First we can start by converting the struture generated with LAMMPS into POSCAR file format
In this case, you can use cfg file format to dump the frames from LAMMPS, which will write the atom types, ...
- 965
2
votes
How to set the LMAXMIX tag in VASP for the material BaLaMn2O6?
DFT+U is an advanced computational method developed specifically to enhance the accuracy of describing systems containing strongly correlated d or f electrons. These systems, such as antiferromagnetic ...
- 965
1
vote
Absorption enthaply at different temprature in VASP software via ab initio molecular dynamics
I will give a general outline on how to perform such caculation. Before we start with the AIMD calculations we need to find the perferred adsorption site/sites according to the following steps:
...
- 965
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