Unanswered Questions
207 questions with no upvoted or accepted answers
22
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0
answers
248
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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
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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
9
votes
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184
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How to do parity analysis of band extrema?
To check whether electronic transitions are allowed between valence band maximum (VBM) and conduction band minimum (CBM) as per Laporte's rule, the parity of VBM/CBM is needed to be known. This paper ...
- 939
7
votes
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answers
106
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What are some open problems to give interns?
Background: I'm a PhD student in Europe. Currently working on method/code development for computational chemistry. I have experience in DFT, code optimization, MD and Machine learning. But I'm not ...
- 1,115
7
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157
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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
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179
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How do you calculate a full quartic force field for anharmonic frequencies?
I am an experimental chemist interested in anharmonicity—I am particularly interested in how to calculate anharmonic frequencies. The method I have the most experience with is (generalised) second ...
7
votes
0
answers
175
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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
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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
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148
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Normalization of the Smooth Overlap of Atomic Positions (SOAP) Kernel
I am using the DScribe implementation (https://singroup.github.io/dscribe/latest/tutorials/descriptors/soap.html) of the Smooth overlap of atomic positions (SOAP) ...
- 543
6
votes
0
answers
106
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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
132
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Free energy calculation as a function of temperature over phase transition
I've run a molecular dynamics simulation (NVT) of a simple Lennard-Jones system of a few particles and I'm trying to calculate the Helmholtz free energy $\Delta F$ as a function of temperature over ...
- 121
6
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70
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Updated book/chapter or review article with broad perspective on computational chemistry
I really like Frank Jensen's "Introduction to Computational Chemistry" because it provides a broad perspective, starting from first principles and extending to surveys of current methods for ...
6
votes
0
answers
77
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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
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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
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0
answers
178
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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