Quantum Espresso Tutorial: h-Boron Phosphide Variable-Cell Relaxation

In summary, the conversation focused on learning how to use Quantum Espresso for simulating a hexagonal boron phosphide primary cell. The user encountered issues with atom distances and Fermi levels, and requested help in checking their input for a variable-cell relaxation calculation. The conversation also briefly mentioned the project being interesting and inquired about progress with the script.
  • #1
Alessandroocj
1
0
Hello my dear fellows, how're you doing? I'm trying to learn how to use Quantum Espresso, and in order to do this, I'm trying to simulate a hexagonal boron phosphide primary cell. At the end of the simulation, the structure seems to be fine, but sometimes the distance of the atoms are too short, and the Fermi level seems to be wrong in all my attempts to solve the problem. I've already tried many different configurations. Could someone gently check my input to see if everything is OK? =)
Here is my input for the variable-cell relaxation

!===========================================================
!
! Quantum Espresso calculation - h-Boron Phosphide
! Variable-cell relaxation
!===========================================================
&CONTROL

calculation='vc-relax'
title='h-bp'
prefix='h-bp'
verbosity='high'
restart_mode='from_scratch'
!nstep=1000
!iprint=1
outdir='./results'
pseudo_dir='./'
!tstress=.true.
forc_conv_thr=1.0d-5
etot_conv_thr=1.0d-6

/

&SYSTEM

ibrav = 0, !lattice is specified below
nat = 2,
ntyp = 2,
ecutwfc = 100.0 ,
ecutrho = 700.0 ,
input_DFT = 'PBE' ,
!occupations = 'smearing',
!degauss = 1.0d-4 ,
!smearing ='marzari-vanderbilt' ,
lspinorb=.true.
noncolin=.true.

/

&ELECTRONS

electron_maxstep = 500,
conv_thr = 1.0d-10,
mixing_mode = 'plain',
mixing_beta = 0.7d0,
diagonalization = 'cg',

/

&IONS
ion_dynamics='bfgs'
upscale=20.0

/

&CELL

! press_conv_thr = 0.5D0
! press = 0.D0
! cell_dynamics = bfgs,
! cell_dofree = '2Dxy'
cell_factor = 3.0D0

/

ATOMIC_SPECIES

B 10.810 B.rel-pbe-n-kjpaw_psl.0.1.UPF
P 30.974 P.rel-pbe-n-kjpaw_psl.1.0.0.UPF

CELL_PARAMETERS (angstrom)

2.1300000 1.2300000 0.0000000
2.1300000 -1.2300000 0.0000000
0.0000000 0.0000000 6.0000000

ATOMIC_POSITIONS (angstrom)

B 0.000000000 0.000000000 3.000000000

P 1.300000000 0.000000000 3.000000000

K_POINTS automatic

12 12 1 0 0 0
 
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1. What is Quantum Espresso?

Quantum Espresso is an open-source software package designed for electronic-structure calculations and materials modeling. It is based on density-functional theory and is widely used in the field of computational materials science.

2. What is h-Boron Phosphide?

h-Boron Phosphide (h-BP) is a layered material composed of boron and phosphorus atoms arranged in a hexagonal lattice. It has potential applications in electronic and optoelectronic devices due to its unique properties.

3. What does "variable-cell relaxation" mean?

In Quantum Espresso, "variable-cell relaxation" refers to the process of optimizing the atomic positions and the shape of the unit cell of a crystal structure simultaneously. This allows for a more accurate and realistic representation of the material's properties.

4. What is the purpose of this tutorial?

The purpose of this tutorial is to guide users through the process of performing a variable-cell relaxation calculation on h-Boron Phosphide using Quantum Espresso. This can help users gain a better understanding of the software and how to use it for their own research.

5. Are there any prerequisites for following this tutorial?

Yes, users should have a basic understanding of Quantum Espresso and density-functional theory. It is also recommended to have some knowledge of Linux operating system and basic programming skills in Fortran or C.

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