Unanswered Questions
171 questions with no upvoted or accepted answers
22
votes
0
answers
248
views
Is there a software that can do derivatives with respect to user defined vibrational modes?
I'm doing some property calculations that depend on a sum of derivatives of some quantity with respect to normal vibrational modes. I was hoping to find some physical intuition relating the type of ...
- 15.9k
9
votes
0
answers
248
views
Different Results obtained while doing multiple runs from same inputs in VASP
I have been trying to optimize the parallelization parameters in VASP. By varying the parameters(such as KPAR and NCORE) I am trying to reduce the Elapsed time that is printed at the end of each line. ...
- 1,701
7
votes
0
answers
157
views
Correct method for structure optimization using DFT tools
Lets's say I want to start off DFT calculations for a material whose experimental cell constants are known. So I have two ways to get the correct structure to later on calculate, say, band structure ...
- 939
7
votes
0
answers
175
views
Is there a way to set the spin multiplicity in a VASP calculation?
I will greatly appreciate if someone can point to whether I can specify the spin multiplicity of a vasp calculation?
I am trying to get the potential energy mapping of a system with neutral slab and a ...
- 551
6
votes
0
answers
117
views
Spin-orbit coupling(SOC) in geometry optimisation
When I tried including SOC during the optimization of InBi lattice constants, the lattice constant increased from 4.6 Å (without SOC) to more than 6 Å (with SOC), which seems like an 'incorrect' ...
- 65
6
votes
0
answers
106
views
What are the parameters in PySCF's Selected Configuration Interaction code
Dear StackExchange Members,
I'm using the native PySCF implementation of selected configuration interaction (SCI). However, I can't seem to find any documentation detailing the algorithm or various ...
- 20.1k
6
votes
0
answers
77
views
Benchmarking DFT vs Experimental Gaps - Confusion over Fundamental and Optical Gaps
Recently, I've come across discussions about the differences between fundamental (or electronic) bandgaps and optical bandgaps, with the two quantities differing mainly by the electron-hole binding ...
- 1,366
6
votes
0
answers
91
views
How can we calculate transverse and longitudinal optical phonon frequencies
Could you please help me to calculate the "transverse and longitudinal optical phonon frequencies" from phonopy+vasp output files?
These parameters will help me to calculate the high-...
- 61
6
votes
0
answers
178
views
DFT+U for RPA Ground State
For RPA calculations in VASP, a four step process can be utilized where the first step is to compute the occupied orbitals at either the GGA or hybrid GGA level.
I am curious with materials that are ...
- 11.6k
5
votes
0
answers
108
views
Help required in reducing VASP memory usage
Good day, I trust you are well and I thank you for taking your time reading through my problem.
I am currently trying to calculate a single point energy calculation with the HSE06 functional for a ...
5
votes
0
answers
67
views
How to choose vacuum value for monolayer and heterostructure?
I have read several articles but I am confused how to choose vacuum in case of 2D materials. Should we add vacuum of 20A in one side of monolayer or 10, 10A on both side of monolayer?
Kindly suggest ...
5
votes
0
answers
41
views
About alignment of 2D monolayer band structures
I need to do the alignment of band structures of one 2D monolayer. I have created some vacancies in the 2D monolayer using VASP and calculated the band gap values (GGA) corresponding to different ...
- 415
5
votes
0
answers
175
views
Problem with using VASP with ase on a GPU
I am a newbie using VASP, currently I am trying to calculate the formation energy per atom and pre bandgap using DFT with VASP on a GPU machine.
I wrote the following script for calculating the ...
- 241
5
votes
0
answers
39
views
How can calculate length or coordinate of any molecule in different quantum state [like (rotational quantum state)j=2] with any software or code?
How can one determine the bond length of a diatomic or tri-atomic molecule(rot. state J=3 and vib. state v=2) from its ground state bond length (x angstrom) using computational tools or programming ...
- 617
5
votes
0
answers
202
views
Optical properties using ESPRESSO's epsilon.x
Currently I'm using epsilon.x from Quantum ESPRESSO to analyse optical
properties of metallic alloys. I'm getting a wiggling curve for the dielectric function.
For the imaginary part of dielectric ...
- 3,394