====== DFT+U Calculation ======

DFT+U calculation for NiO

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

atom.config

<code bash>
           4
 Lattice vector
       4.1700000000      2.0850000000      2.0850000000
       2.0850000000      4.1700000000      2.0850000000
       2.0850000000      2.0850000000      4.1700000000
 Position, move_x, move_y, move_z
   28    0.000000000000    0.000000000000    0.000000000000  0  0  0
   28    0.500000000000    0.500000000000    0.500000000000  0  0  0
    8    0.250000000000    0.250000000000    0.250000000000  0  0  0
    8    0.750000000000    0.750000000000    0.750000000000  0  0  0
</code>

etot.input

<code bash>
   1  4
   JOB = SCF
   IN.PSP1 = O.SG15.PBE.UPF
   IN.PSP2 = Ni.SG15.PBE.UPF
   IN.ATOM = atom.config
   SPIN = 2
   Ecut = 50
   MP_N123 = 5 5 5 0 0 0
   LDAU_PSP2 = 2 4.3 # LDAU_L, Hubbard_U, (optional Hubbard_U2)
</code>

LDAU_PSP(i): specifies DFT+U method, LDAU_PSP2 means add U for Ni element. LDAU_L: selects l quantum number for which on site interaction is added; Hubbard_U: the strength of the effective on-site Coulomb interactions.


O.SG15.PBE.UPF, Ni.SG15.PBE.UPF

O.SG15.PBE.UPF, Ni.SG15.PEB.UPF are the pseudopotential files.


===== Calculations =====

  - You can submit PWmat tasks in different ways:

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

<wrap round tip> Run the command directly </wrap>

<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>

<wrap round tip> Submit the task with a pbs script </wrap>

  - For DFT+U calculation, you can read total energy resulting from calculations with DFT+U.

<code bash>
grep "E_tot(eV)" REPORT | tail -1
>>> E_tot(eV)    = -.92278062603732E+04    -.4049E-04
</code>