Questions tagged [quantum-espresso]

Questions related to the open source materials modeling framework, Quantum Espresso.

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29 votes
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Quantum ESPRESSO vs VASP

We know that both Quantum ESPRESSO and VASP can perform lots of different kinds of simulations of materials. But what can VASP do that Quantum ESPRESSO can not, and vice-versa?
Anibal Bezerra's user avatar
23 votes
3 answers
932 views

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 ...
Cody Aldaz's user avatar
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23 votes
1 answer
2k views

Why is the band structure of a supercell more dense than for simple cell?

In order to do DFT calculations of metallic alloys, the start point is a supercell, whose atoms are changed to match the desired stoichiometry. Gold and Silver, for example, both have FCC structure. ...
Anibal Bezerra's user avatar
21 votes
3 answers
4k views

k-points and ENCUT convergence tests before or after relaxation?

Let's say I want to relax a structure using VASP. K-points and ENCUT convergence tests must be conducted before or after relaxation? and which tags should be ...
Chi Kou's user avatar
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9 votes
1 answer
5k views

What is the physical meaning of occupations='smearing' in Quantum ESPRESSO?

I want to understand, what is the intuition behind using the occupations='smearing' or 'tetrahedra' in Quantum ESPRESSO input file? I mean how we can interpret what is going to happen inside of ...
UJM's user avatar
  • 2,591
5 votes
1 answer
764 views

How to calculate DOS and band structure using hybrid functional in Quantum Espresso?

After I run an SCF calculation with PBE0, I want to use calculation= 'nscf'/ (‘bands’) with PBE0, but this message occurs: ...
SOELHADFI's user avatar
  • 431
24 votes
2 answers
7k views

What are some good band-structure/DOS plotting tools/styles?

I am currently using p4vasp for drawing DOS and band-structure plots, but it is not much handy in modifying the OUTPUTS. Could you please suggest any other good software or tools for that?
Chi Kou's user avatar
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21 votes
9 answers
9k views

How to master Fortran with minimal effort?

Fortran language is used in many first-principles matter modeling codes, such as VASP and QE. These codes usually include many ...
Jack's user avatar
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21 votes
2 answers
5k views

What is the difference between Ultrasoft, ONCV and PAW Pseudopotentials? Which is better for a spin-orbit coupled calculation?

I am trying to do spin-orbit coupled calculations for various topological insulators. I have found papers using Quantum Espresso with ONCV pseudopotentials and papers using VASP with PAW ...
Ashique Lal's user avatar
  • 1,601
20 votes
2 answers
11k views

Calculating HSE06 band structures on Quantum ESPRESSO

I am currently trying to figure out how to compute band structures for my system, using the hybrid functional HSE06. I'm doing this on Quantum Espresso. As I understand, there are a handful of ways to ...
livars98's user avatar
  • 2,456
17 votes
1 answer
1k views

Are there problems with the Tran-Blaha modified Becke-Johnson potential (mBJ, a.k.a. TB09) in Quantum ESPRESSO?

I have used the modified Becke-Johnson (mBJ) exchange potential before, as it was developed and implemented in Wien2K by Fabien Tran and Peter Blaha (1). In 2013, Éric Germaneau et al. implemented mBJ ...
epalos's user avatar
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14 votes
3 answers
6k views

Should I connect 2-3 laptops to form a supercomputer?

I have recently started to use Quantum ESPRESSO for evaluating different properties of ZnSe Quantum Dots. But I currently don't have access to any cluster and as I am increasing the size of ...
Parmeet Singh EP 066's user avatar
13 votes
4 answers
3k views

How to make a k-point convergence test for a bulk structure with a lower k-point in the z-direction?

Let's say I want to make k-point convergence test for graphite. And let's say it converges at 12x12x4. Do I first need to do a k-point convergence test for equal k-points on xyz directions then make ...
Taavi's user avatar
  • 131
12 votes
1 answer
417 views

What is the best program to manipulate numerical DFT wavefunctions to calculate custom matrix elements?

For pedagogical reasons, I am looking for ways to calculate quantum-mechanical quantities such as $\langle m | \dot{m}\rangle, \langle m | \dot{n}\rangle, \langle m | \ddot{n}\rangle$ using ...
TribalChief's user avatar
  • 2,321
12 votes
2 answers
9k views

What is the difference between DOS and PDOS?

I'm new to DFT. Can you please help me to understand DOS and PDOS (projected density of states) in simple wording? I only want to know some basics of these terms and how they are linked to DFT.
Areej Sahar's user avatar
9 votes
3 answers
902 views

For which elements should I include spin orbit coupling in Quantum ESPRESSO?

I'm trying to study a Yb-Ge-Sb compound and would like to include spin-orbit coupling (SOC). In Quantum ESPRESSO, this is done by including the following tags in the ...
JasonDavis's user avatar
9 votes
1 answer
1k views

If total energies differ across different software, how do I decide which software to use?

I posted a question previously about why I got different total energy values when I ran a DFT calculation with quantum espresso compared to VASP (link to the question). From what I understood from the ...
Yonatan Kurniawan's user avatar
8 votes
1 answer
485 views

What is the best way to compute the DFT total energy and atomic forces for given atomic positions?

I am new to DFT calculation and I want to compute DFT total energy and atomic forces of an atomic configuration, given the atomic positions and lattice vectors. I have an extended xyz with DFT energy ...
Yonatan Kurniawan's user avatar
8 votes
1 answer
521 views

How to extract the Pressure, Energy and unit-cell volume from quantum ESPRESSO output file using bash script?

I needed the Energy and Volume values for predicting the bulk modulus of a crystal via the Birch Murmaghan equation. Can I get a bash script for doing the same.
Anoop A Nair's user avatar
  • 4,458
5 votes
1 answer
426 views

Convert PSP8 pseudopotential files to UPF format

Is there a way to convert psp8 pseudopotential files (used for abinit) to UPF format (used for Quantum ESPRESSO)? I noticed there is the upfconv.x utility in ...
fgoudra's user avatar
  • 151
20 votes
2 answers
1k views

Norm-Conserving or Ultrasoft, which pseudopotential to choose?

Ultrasoft pseudopotential (USPP), in general, requires a lower energy-cutoff to the plane waves when compared to Norm-Conserving ones (NC). On the other hand (at least with Quantum ESPRESSO) the ...
Anibal Bezerra's user avatar
19 votes
3 answers
2k views

Running Quantum ESPRESSO calculations in Google Colab

So one big problem I experience in doing calculations with Quantum ESPRESSO is that many calculations require a lot of computing power: you need large RAM capacities and powerful processors especially ...
jboy's user avatar
  • 1,131
18 votes
2 answers
557 views

Calculating binding energy between two systems

Regarding the calculation of binding energy of molecular absorption on graphene, for which this has been discussed before, the process of calculating $E_{AB}$ is fairly straight forward, i.e., it is ...
Shahid Sattar's user avatar
17 votes
1 answer
1k views

How does the mBJ potential give an accurate band gap as compared to LDA and GGA?

I am not able to understand the literature on how the modified Becke-Johnson(MBJ)$^{[1]}$ potential gives an accurate bandgap. Can someone please help? Thank you. The formula for the potential can be ...
sonia rani's user avatar
13 votes
1 answer
3k views

How to do spin polarization calculations using Quantum ESPRESSO?

I am currently new to DFT calculations in Quantum ESPRESSO. Though, I have read some research papers for determining spin polarization and Half-metallicity in certain Heusler alloys. These research ...
UJM's user avatar
  • 2,591
13 votes
5 answers
9k views

How to know optimal K-points grid values for good DFT calculation?

I am doing DFT calculations with pw.x executable in Quantum Espresso. For this we have to choose right K-points grid in order to perform error-less calculation. But I have no idea about how can I ...
UJM's user avatar
  • 2,591
13 votes
1 answer
1k views

Why is the Nonequilibrium Green’s function (NEGF) method for quantum transport not implemented in plane wave codes like VASP and Quantum Espresso?

DFT codes like Siesta, QuantumATK, Questaal, and Smeagol having localized basis sets have NEGF implementations available. But not in plane wave codes like VASP and Quantum Espresso. Why is it so?
Thomas's user avatar
  • 8,952
12 votes
3 answers
2k views

How can I submit jobs to an HPC scheduler?

It is my first time trying to use an HPC system and I am a bit overwhelmed. I have gone through a course on using HPC systems on Coursera and have a basic idea about using Linux. Could you guys tell ...
Parmeet Singh EP 066's user avatar
12 votes
1 answer
7k views

When should "vc-relax" be performed over "relax" calculations in Quantum ESPRESSO?

I'm new to Quantum ESPRESSO and I have read that there are several scenarios when relax calculations are preferred over vc-relax calculations, for example in maintaining vacuum while modelling surface....
Anoop A Nair's user avatar
  • 4,458
12 votes
2 answers
685 views

Recommended code to do XAS/XES/RIXS calculations with?

I am a grad student looking to simulate several XAS/XES and potentially RIXS spectra for some strongly correlated metal-oxides. The materials in question will likely require solving the Bethe-Salpeter ...
Haru Fujimura's user avatar
11 votes
1 answer
1k views

How to calculate the energy of conduction band and valence band with respect to vacuum in quantum espresso?

I was able to calculate band energies in quantum espresso. How to convert them to values that are in terms of difference from vacuum energy?
Ashique Lal's user avatar
  • 1,601
11 votes
1 answer
321 views

Geometrical Optimization not converging, where am I going wrong?

I am trying to obtain the optical properties of ZnSe Quantum Dots, the problem is that my geometrical optimization is not converging. I used VESTA to create the structure(there is a photo in the ...
Parmeet Singh EP 066's user avatar
11 votes
2 answers
1k views

Is there an energy gap correction factor that needs to be used in DFT calculations?

I am a beginner and have performed the DFT calculation in Quantum ESPRESSO for calculation of the direct and indirect bandgap of Silicon. I found the indirect bandgap to be 0.6551 eV. Now, I have ...
UJM's user avatar
  • 2,591
11 votes
1 answer
1k views

Is the "Final Magnetic moment" in the materials project repository same as the "total magnetization" value in Quantum ESPRESSO output files?

I'm quite new to spin-polarized DFT and have been trying to study $BaVSe_{3}$ which is ferromagnetic (with a Final Magnetic Moment of 0.052 Bohr Mag) as per the Materials Project repository [picture 1]...
Anoop A Nair's user avatar
  • 4,458
10 votes
1 answer
1k views

How to understand the wavefunction outputed by QE with HDF5 format?

Following the answer to my question: What is the best program to manipulate numerical DFT wavefunctions to calculate custom matrix elements?, I compiled Quantum ESPRESSO with the hdf5 flag on, and now ...
TribalChief's user avatar
  • 2,321
10 votes
3 answers
3k views

Installing Quantum ESPRESSO on an Apple M1 processor possible?

I'm attempting to make QEspresso's pw program on a new 2021 MacBook Air, which has an M1 processor. While ./configure does not throw any errors, running 'make pw' fails with the following output: <...
Paul Eugenio's user avatar
9 votes
1 answer
452 views

Different band structure in supercell, but not due to band folding

This is my first time asking a question - if I mess something up please let me know and I'll amend. I believe this goes beyond questions on how to use QE so here seems appropriate over the QE forums. ...
MSteg's user avatar
  • 311
9 votes
2 answers
888 views

How to obtain spin projected band structure for system with Spin Orbit Coupling?

Spin-orbit coupling[1] means the system has a non-collinear spin. Therefore, spin exists as a spinor, hence there is no meaning to 'up' and 'down' spin. Still, is there any way to get fat-band plot ...
Ashique Lal's user avatar
  • 1,601
9 votes
1 answer
497 views

Should I use a lower threshold for calculations involving SOC?

I'm studying a compound $\ce{VSe_2}$ using the DFT package Quantum ESPRESSO (QE). The following is the input file. ...
Atom's user avatar
  • 957
8 votes
3 answers
764 views

Cu FCC vc-relax method error

Reference: Density Functional Theory: A Practical Introduction, David Sholl, Janice A. Steckel, Chapter 2, Page No. 48 Section 2.2 The fcc Cu calculations in Fig. 2.3 used a cubic supercell with 4 Cu ...
147875's user avatar
  • 663
8 votes
1 answer
249 views

Do NSCF calculations on Supercell gives different band gap than the Unit Cell?

NSCF (non-self-consistent field) calculations are done on a dense mesh. I did it on a unit cell. Then since I have to try using a supercell for alloying, I am doing calculations to see the results of ...
epsilon02fft's user avatar
  • 1,392
8 votes
0 answers
265 views

Bloch wave function extraction for the specific k-points and specific band from QE calculation [closed]

I would like to use QE to obtain u_K(r), which is the Bloch wave function of spin-up maximum valance band at K point. If I define the K point in the input file and do an SCF calculation by QE ...
user3993's user avatar
7 votes
1 answer
827 views

How do I install Quantum ESPRESSO on Linux?

People, can someone please help me how to solve this problem with QE 7.0 installation:
Everson Gomes's user avatar
7 votes
1 answer
2k views

Running Quantum ESPRESSO on a GPU in Windows

I have been using BURAI GUI for Quantum ESPRESSO for the calculation of optical properties of ZnSe. While running calculations I observed that my laptop's GPU was not even being used and I am a bit ...
Parmeet Singh EP 066's user avatar
6 votes
1 answer
520 views

How to construct thin film structure of desired thickness in quantum espresso?

I want to study the properties of thin films using DFT calculation. I have done the bulk crystal calculations in Quantum ESPRESSO but have no idea how can I construct the thin film of desired ...
UJM's user avatar
  • 2,591
5 votes
0 answers
257 views

Cif2QE (QEtoolkit): Error when using this input file for (221) MoS2 monolayer [closed]

My input file for the (221) $\ce{MoS2}$ monolayer was created through Cif2QE (QEtoolkit): ...
Nithyadevi's user avatar
5 votes
1 answer
321 views

How to calculate the charge density using Quantum Espresso?

How do I modify the input file below to calculate the charge density (DENS) using Quantum Espresso? Input file: ...
Caroline Santos 's user avatar
5 votes
1 answer
181 views

How to make ferro, feri and antiferro magnetic structure for QE

I have below &SYSTME information from my input file ...
astha's user avatar
  • 1,663
5 votes
1 answer
99 views

Translate between ibrav and space_group Quantum Espresso inputs

I am attempting to utilise the space_group option for potential performance speed-up. In this I have two Q.E. files which I hope would give equivalent results; ...
Wychh's user avatar
  • 2,147
5 votes
1 answer
374 views

Quantum Espresso calculation for Deuterium

I am a new user of Quantum Espresso. I have to use Deuterium instead of Hydrogen for my work in DFT studies. Hydrogen Pseudopotential file is available in QE website. Please clarify what parameters I ...
Nithyadevi's user avatar