====== SCF calculation ======

SCF calculation for Si

===== Input files =====

atom.config

<code bash>
        2
 LATTICE
      0.00000000     2.71535000     2.71535000
      2.71535000     0.00000000     2.71535000
      2.71535000     2.71535000     0.00000000
 POSITION
  14     0.00000000     0.00000000     0.00000000 0 0 0
  14     0.25000000     0.25000000     0.25000000 0 0 0
</code>

<note>
Note 1. atom.config file describles the cell box, atomic postitions, etc. 2. 2 atoms per unit cell. 3. LATTICE: the header of the lattice vector. 4. POSITION: the header of the atomic positions. :::
</note>

etot.input

<code bash>
   1 4
   JOB = SCF
   IN.PSP1 = Si.SG15.PBE.UPF
   IN.ATOM = atom.config
   ECUT = 50
   MP_N123 = 9 9 9 0 0 0
</code>

<note>
Note 1. The product of the two integers on the first line must equal to the number of GPU to run PWmat. 2. ECUT is the plane wave cutoff energy of wavefunction (in //Ryd//, note: 1 //Ryd// = 13.6057 //eV//) 3. MP_N123 is the Monkhorst-Pack grids to generate the reduced k-points, so no additional k-points file is required. :::
</note>

Si.SG15.PBE.UPF

<code>
tip Note Si.SG15.PEB.UPF is the pseudopotential file.
</code>

===== Calculations =====

1.You can submit PWmat tasks in different ways:

<code bash>
   mpirun -np 4 PWmat | tee output
</code>

:::tip Note Run the command directly :::


----

<code bash>
   #!/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
</code>

<note>
Note Submit the task with a pbs script
</note>

  - For SCF calculation, the main output is REPORT file, you can read total energy and calculation time from it.

<code bash>
   grep "E_tot(eV)" REPORT | tail -1
   > E_tot(eV)    = -.21456142286654E+03    -.3243E-05
</code>

<code bash>
   grep "total computation time" REPORT
   > total computation time (sec)=   10.0428440570831
</code>

===== Download =====

[[https://github.com/LonxunQuantum/Q-CAD-documentations/blob/master/source/Examples/examples/Si_SCF_Cal.tar.gz|Si_SCF_Cal]]