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Dimer method to calculate saddle point

H diffusion in a frozen Ir lattice

Input files

atom.config

     5
LATTICE
3.84347853 0.00000000 0.00000000
0.00000000 3.84347853 0.00000000
0.00000000 0.00000000 3.84347853
POSITION
77 0.12500000 0.12500000 0.12500000 0 0 0
77 0.12500937 0.63473653 0.63473930 1 1 1
77 0.63473766 0.12500788 0.63474031 1 1 1
77 0.63473926 0.63473848 0.12501068 1 1 1
1 0.47985749 0.47985229 0.47985339 1 1 1
DIMER_DIR_N
77 0.000000000000000 0.000000000000000 0.000000000000000 #element number, fractional coordinates of direction
77 -0.012059410733252 -0.012827111941020 -0.008025300664088
77 -0.013847872075022 -0.009967273033432 -0.007927057981427
77 -0.013434331335085 -0.012626295573776 -0.003144488942515
1 0.071022910801012 0.074799719412651 0.085081889050619
tip

DIMER_DIR_N: specifies the initial direction along the dimer.

etot.input

 1  4
JOB = DIMER
IN.ATOM = atom.config
IN.PSP1 = Ir.SG15.PBE.UPF
IN.PSP2 = H.SG15.PBE.UPF
ECUT = 50
ECUT2 = 200
MP_N123 = 5 5 5 0 0 0 3
E_ERROR = 0.0
FERMIDE = 0.2
tip

JOB = DIMER: specifies a calculation of dimer method.

Ir.SG15.PBE.UPF, H.SG15.PBE.UPF

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 DIMER calculation, the final configuration is writen in final.config, the configurations of each translation step ore in MOVEMENT.

  2. Another file DIMERSTEPS can be used to check the convergency, dates in DIMERSTEPS:

STEP         FORCE      FORCE/dR        ENERGY     CURVATURE         ANGLE        NSTEPS      DISTANCE
MAX(eV/Ang) ROT(eV/Ang^2) (eV) ROT ROT TRANS
1 0.97540 3.24074 -11578.64674 -0.04126 0.04787 1 0.10000
2 0.33231 1.08127 -11578.67713 -0.03043 0.03043 1 -0.07131
3 0.40229 1.16503 -11578.67639 -0.02366 0.01931 1 0.02685
4 0.19611 0.94741 -11578.68556 -0.02616 0.01533 1 0.10000
5 0.19684 0.70913 -11578.68577 -0.02493 0.01250 1 -0.00189
6 0.21610 1.98167 -11578.68433 -0.02524 0.02234 1 0.10000
7 0.15590 1.31524 -11578.68344 -0.02669 0.01483 1 0.03999
8 0.27853 1.01864 -11578.68047 -0.02487 0.01141 1 0.04234
9 0.07919 0.72661 -11578.68151 -0.02434 0.01165 1 0.02893
10 0.07897 0.88689 -11578.68147 -0.02679 0.01048 1 0.00062
11 0.08531 0.57502 -11578.68097 -0.02615 0.00763 1 0.01706
12 0.02929 1.68360 -11578.68063 -0.02664 0.02057 1 0.03746 *
Note
  1. STEP: the index of current transition step.
  2. FORCE MAX: the maximum of current transition step, unit eV/A˚eV/\text{\AA}.
  3. FORCE ROT/dR: the rotational force / dimer_dR, unit eV/A˚2eV/\text{\AA}^2.
  4. ENERGY: the energy of the dimer center, unit eV.
  5. CURVATURE: the curvature along the dimer.
  6. ANGLE ROT: the number of rotated in rotational steps, unit rad.
  7. NSTEPS ROT: the number of rotational steps in current transiton step.
  8. DISTANCE TRANS: the step size of current transition step, unit Bohr.