Tanmay's Research Blog

Error during vc-relax calculation in parallel This error is a problem with the input file, this place is because &CELL ... / An additional 3 spaces were entered between the following module, causing it to generate an exception when reading the input file. It is best not to have extra spaces in the input file. In addition, such problems usually leave a file of input_tmp.in in the workspace. Ref: https://lists.quantum-espresso.org/pipermail/users/2019-March/042248.html https://github.com/LCPQ/quantum_package/issues/184 http://www.programmersought.com/article/87821528671/

Error in routine pw_readschemafile (1): xml data file not found Arises while running band structure calculation This error occurs when bands.in file can not read some data from the nscf run. The files might not be in the correct directory and not have the same filename/prefix etc. Ref:

This error arises while running scf calculation in parallel & solved by putting diagonalization='cg' ; in the input file

Method Step 1 I have taken CIF file (Primitive Cell) for both ZnO & MoS2 from  materials cloud Step 2 Both the CIF file was imported inside VESTA and MoS2 was put on ZnO (10-10) plane by giving the suitable (h, k, l) value (Click here to know how to find it) Step 3 Now to find out suitable scaling In the vertical direction, we have to match the P( perpendicular distance as shown in the fig below) with c of ZnO. In Horizontal direction, In the case of MoS2, the repeating structure is two red stars and the distance between them is found to be 2.42 Angstrom, which we need to match with 'a' of ZnO. When we scale-up MoS2 we have to scale 9 times in horizontal direction instead of 7, since it will be insufficient to cut the MoS2 sheet later but since we are scaling ZnO to be 5 times so we can directly cut MoS2 matching  it with ZnO supercell as below Now we have to cut MoS2 in such a way that it will be periodic at the boundar

We generally go through a smaller system like 'Si' learn the basics of computational methods, but for our applications in our research, we need to model a more complex system. So I had come across some tools to model systems for Quantum Espresso. 1. VESTA 2. ChemDraw 3. Mercury In some cases also we can use BURAI  to model our system using the modeler tools provided in it. 1.  In  VESTA  we can model different types of solid-state systems including Interfaces. Here are some important tutorials  Supercell construction and adding Vacuum in Vesta - Ruthenium Make a heterostructure or interface using Vesta If you go through the details of these contents then you can have an idea to make your own multilayer or Interface system which can be comparable with Quantum Espresso. To model any kind of structure, 1st we need the crystallographic information. So we give CIF file as input to the VESTA software. Here are some places from where you

When I had started learning the basics behind Quantum Espresso, I had come across some very useful resources. Most of them are from Quantum Espresso Tutorial  available on the Quantum espresso website and YouTube. For a beginner, I would like to recommend this amazing seminar by Astrid Marthinsen Here she has beautifully explained all the basics one needs to start working with Quantum Espresso. There are some GUIs available for Quantum Espresso in both windows & Ubuntu operating system  1. BURAI   2. PWgui If you are just starting to learn Quantum Espresso then as per my experience  BURAI   can be a good place to start because here you can get some simpler system with auto-generated input file to start with. So here you will not face any error due to directory or Pseudopotential etc (Unlike PWgui), which may be difficult to deal with initially so you can fully concentrate on learning the input file structure only. I had found this YouTube channel ( Ph

In Quantum Espresso, all the Pseudo Potentials should of the same type The best place to find the Pseudo Potential is Quantum Espresso Official Site https://www.quantum-espresso.org/pseudopotentials In some cases, we can not find the required Pseudo Potentials, so here are some alternative I have come across 1.  Materials Cloud 2.  Pseudo-dojo 3.  mirrors.xtom.com 4. Davide Ceresli PP 5. Theos 6.  JDFTx 7. GitHub

When we run our Quantum espresso calculation in a supercomputer, we use a bash script (script.sh) which looks similar to the script given below #!/bin/bash #SBATCH --job-name=ufslab #SBATCH --nodes=3 #SBATCH --tasks-per-node=40 #SBATCH --partition=standard #SBATCH --output=scf_cn65.out #SBATCH --time=72:00:00 module load intel/2018.5.274 module load quantum_espresso_6.4.1 time mpirun -np  128  pw.x  <scf.in ZnO (4X4) Supercell If you are a beginner, then you might be wondering about the parameters that you should give like the number of nodes ( nodes ) ,  tasks per node, number of processors  -np for your calculation. So here I am going to share my analysis data for a ZnO 4X4 input file, from where you can have a better understanding of how it's working.  Calculation time in second for different script parameter@ZnO_4X4 Here you can see that I have run the calculation in a number of nodes starting from 1 to 16 for the different number