Questions tagged [plane-waves]

Questions about plane-wave basis sets.

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3 votes
0 answers

total spin (J-resolved) projected band structure with SOC

I have been asked by a colleague if it is possible to calculate the spin-projected band structure (with SOC) for a material he is studying. He referenced a paper Boschini et al. Sci. Reports 2015 - ...
1 vote
0 answers

MPI error in Quantum Espresso during optimization of particularly large molecules

I have been recently trying to optimize a particularly large system Mo2C in QE using the pw.x executable and encountering the following MPI errors: ...
2 votes
0 answers

Running out of RAM memory in relax calculation using Quantum Espresso [closed]

I am doing a relax calculations of a 160 gold atom cubic cell using 126GB of RAM space on one node using quantum espresso. but the calculations fails with out-of-memory error. I have tried using ...
3 votes
1 answer

In a plane-wave code, does the Fermi energy depend on the pseudopotentials used?

I am planning to do some work using grand-canonical DFT, I believe that the Fermi energy depends on the pseudo-potentials used (like the total energy). My understanding is that the Fermi energy has to ...
7 votes
1 answer

Mixing pseudopotentials with gaussian and plane wave basis

I am somewhat of a novice in computational chemistry of materials, and have been tasked to replicate simulations from a relevant paper. The paper is a bit scant on details so I am trying to recreate ...
4 votes
1 answer

Compute solvation energies with (ESM) RISM-SCF

I want to use the 3D-RISM-SCF and ESM-RISM implementation in Quantum Espresso to compute solvated adsorption energies and absolute solvation energies. Before starting I read the main paper by S. ...
1 vote
0 answers

how to choose a basis set when calculating COHP? [closed]

I am trying to use the lobster program to calculate COHP, according to the explanation in the literature, it is better to add unoccupied atom orbitals into the basis set. The initial step in ...
2 votes
0 answers

Force convergence in Wannier orbitals based DFT code [closed]

I am working on Pt(111) / nanoparticles with various ligands, I am mainly using two softwares: A well known general purpose plane-wave code (Quantum Espresso). A less known software that is also ...
11 votes
0 answers

How to solve general wave equation and dispersion relation using Fourier series? [closed]

In this paper (open access), the authors used Fourier series with most general wave equation to find the dispersion relation. I am presenting some main equations as snippets to depict their solution. ...
9 votes
1 answer

Simulation of charged species with plane-waves in Quantum Espresso

I am using Quantum Espresso to simulate a platinum surface with ligands, so far everything is working ok. I now need to introduce a solvated hydronium $\ce{H_3O^+(H_2O)_2}$. Is there something I ...
17 votes
1 answer

Linearized Augmented Plane Wave Method vs. Pseudopotential Methods

While reviewing some DFT literature, I have come across a few papers utilizing the LAPW (Linearized Augmented Plane Wave) method, but I am interested in understanding why exactly one would use these ...
10 votes
1 answer

Energy cut-off test meaning in atomic-like basis functions' DFT

I have been using SIESTA code to perform some practicals in my college and I have run energy cut-off tests before calculating properties of semi-conductors or insulator. As far as I am concerned, ...
14 votes
2 answers

When are atomic-orbital-basis (rather than plane-wave) methods appropriate in periodic DFT?

For example, GPAW supports both plane-wave and atomic-orbital basis methods. I know that atomic-orbital basis methods can have difficulty with electrons occupying vacancies for example, but what ...
14 votes
1 answer

Is basis set superposition error reduced when using the GAPW method?

CP2K implements the Gaussian and Augmented Planewaves (GAPW) approach for all-electron calculations. My understanding is that the GAPW method involves using atom-centered Gaussian type orbitals to ...
9 votes
2 answers

Suggested cutoff for high level VASP calculations

I am new at VASP, and apparently, cutoff convergence is not something like kpoint convergence. Is using ENCUT=1.5xENMAX can be justified? For RPA, GW and MP2 ...
12 votes
2 answers

Are meta-GGA functionals SCAN (and its variants) ok to use in planewave DFT with the PBE pseudopotentials?

The meta-GGA SCAN functional has been there for a while. Despite the lack of SCAN (ultrasoft/PAW) pseudopotentials, various works used it in plane-wave pseudopotential calculations with ...
23 votes
3 answers

How to do periodic DFT calculations using Quantum ESPRESSO?

I have only done quantum mechanical computations using non-periodic wavefunctions. I'd like to try to periodic-wavefunction density functional theory. Quantum ESPRESSO seems like a good package ...