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Crystal Structure Optimization (both atomic position and cell shape)

RELAXATION calculation for graphene, both relax atomic postion and cell shape

Input files

atom.config

     4
LATTICE
2.46596583 0.00000000 0.00000000
-1.23298291 2.13558905 0.00000000
0.00000000 0.00000000 6.41151115
POSITION
6 0.00000000 0.00000000 0.75000000 1 1 1
6 0.66667000 0.33333000 0.75000000 1 1 1
6 0.00000000 0.00000000 0.25000000 1 1 1
6 0.33333000 0.66667000 0.25000000 1 1 1
STRESS_MASK # optional
1 1 1
1 1 1
1 1 1
提示

STRESS_MASK: used to multiply to the stress tensor for cell relaxation, so some directions of the cell can be fixed.

etot.input

   1  4
JOB = RELAX
IN.PSP1 = C.SG15.PBE.UPF
IN.ATOM = atom.config
RELAX_DETAIL = 1 100 0.01 1 0.02 #IMTH, NSTEP, FORCE_TOL, ISTRESS, TOL_STRESS
VDW = DFT-D2
Ecut = 70
Ecut2 = 280
MP_N123 = 12 12 4 0 0 0
提示
  1. ISTRESS: controls whether to relax the lattice vectors.
  2. TOL_STRESS: is the stress tolerance for the maximal residual stress (eV/Natom).
  3. VDW: used to specfiy the type of Van Der Waals correction.

C.SG15.PBE.UPF

提示

C.SG15.PEB.UPF is the pseudopotential file.

Calculations

  1. You can submit PWmat tasks in different ways:
   mpirun -np 4 PWmat | tee output
Note

Run the command directly

   #!/bin/bash
#PBS -N SCF
#PBS -l nodes=1:ppn=4
#PBS -q batch
#PBS -l walltime=100:00:00

ulimit -s unlimited
cd $PBS_O_WORKDIR

mpirun -np 4 PWmat | tee output
Note

Submit the task with a pbs script

  1. For RELAXATION calculation, files to watch during relaxations.

RELAXSTEPS: concisely reports about the atomic relaxation steps. A typical RELAXSTEPS file looks like:

   It=   -1  CORR E=  -0.6210369947615E+03  Av_F=  0.40E-03 M_F=  0.60E-03 Av_e=  0.22E+00 dE=   0.2E-05 dRho=   0.1E-03 SCF=    13 dL=  0.00E+00 d_AL=  0.14-320 p*F=  0.00E+00 p*F0=  0.00E+00 Fch=  0.00E+00
It= 0 NEW E= -0.6210387518836E+03 Av_F= 0.15E-02 M_F= 0.22E-02 Av_e= 0.14E+00 dE= 0.2E-04 dRho= 0.2E-03 SCF= 4 dL= -0.62E-04 d_AL= 0.21E-01 p*F= 0.51E-02 p*F0= -0.14E-02 Fch= -0.14E+05
It= 1 CORR E= -0.6210399476706E+03 Av_F= 0.71E-03 M_F= 0.11E-02 Av_e= 0.23E-01 dE= 0.2E-03 dRho= 0.1E-04 SCF= 2 dL= -0.38E-04 d_AL= 0.83E-02 p*F= 0.25E-02 p*F0= -0.14E-02 Fch= -0.14E+06
It= 2 CORR E= -0.6210399448332E+03 Av_F= 0.72E-03 M_F= 0.11E-02 Av_e= 0.23E-01 dE= 0.1E-06 dRho= 0.4E-05 SCF= 2 dL= -0.38E-04 d_AL= 0.73E-04 p*F= 0.25E-02 p*F0= -0.14E-02 Fch= -0.13E+06
...
It= 10 CORR E= -0.6210403273943E+03 Av_F= 0.21E-02 M_F= 0.32E-02 Av_e= 0.39E-02 dE= 0.4E-04 dRho= 0.5E-05 SCF= 2 dL= -0.11E-02 d_AL= 0.21E-02 p*F= 0.73E-02 p*F0= -0.11E+00 Fch= 0.17E+01
It= 11 *END E= -0.6210403273943E+03 Av_F= 0.21E-02 M_F= 0.32E-02 Av_e= 0.39E-02 dE= 0.4E-04 dRho= 0.5E-05 SCF= 2 dL= -0.11E-02 d_AL= 0.21E-02 p*F= 0.73E-02 p*F0= -0.11E+00 Fch= 0.17E+01

REPORT: more detailed information about every electronic and ionic step

OUT.STRESS: stess tensor (eV/Naom), for cell relaxation, the stress tensor will calculated and written in OUT.STRESS.

  1. Other important files.

final.config: holds the structure of the last ionic step, the structural result (also very important for restarting a relaxation)

MOVEMENT: holds the structures of every ionic step during relaxations.