Questions tagged [quantum-espresso]
Questions related to the open source materials modeling framework, Quantum Espresso.
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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 ...
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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 ...
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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?
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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?
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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. ...
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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 ...
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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 ...
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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:
...
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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 ...
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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 ...
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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 ...
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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 ...
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What is the best program to manipulate plane-wave 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 ...
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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.
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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....
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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.
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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 ...
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How do I install Quantum ESPRESSO on Linux?
People, can someone please help me how to solve this problem with QE 7.0 installation:
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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 ...
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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:
...
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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 ...
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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 ...
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18
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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 ...
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Physical interpretation of k-points
What is the Physical interpretation of the k-points used in ab initio calculations? Why must the number of k-points be optimized rather than just using some large fixed number of them?
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How do we know how much computational power is required for a particular calculation?
So I am super new, although I have gotten the hang of using DFT in Quantum Espresso. I am having a problem with running the calculation for 1.6 nm ZnSe quantum dot. I haven't even gotten to ...
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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 ...
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5
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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 ...
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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?
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How to calculate the effective mass from DFT band calculations?
One of the properties used in Solid State Physics, and specially in semiconductor physics, is the effective mass. It can be calculated from the energy dispersion relationship. The simple form, for ...
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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]...
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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.
...
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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:
<...
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Raman Spectra in Quantum Espresso
Does anyone have any experience simulating Raman spectra in Quantum ESPRESSO? Following the example 15 that comes with QE, I have attempted to simulate the Raman spectrum of MgO. I know the lraman ...
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Pressure applied DFT calculations in Quantum ESPRESSO
I am trying to perform the pressure-induced DFT calculations in Quantum ESPRESSO. For this, I have calculated the lattice constant of the cubic structure by vc-relax...
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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 ...
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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.
...
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How to read QE's wfc*.dat files with python
I'm working with QE 7.0 for the computation of some properties of solids.
My working theory requires me to access all the information inside the wfc#c.dat/h5 files, created in the prefix.save ...
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How to select the projections and inner/outer window for Wannier90 calculations?
I am new to Wannier90 calculations. I am trying to obtain the Wannier functions and Wannier interpolated band structure.
But I am having a problem in setting the parameters like ...
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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 ...
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