[Pw_forum] VC-Relaxation

[Diep Vinh Quang]

Hi all,

How can we using the Variable Cell Relaxation programe. I have the
following input file for pw.x but after some time, the propram stop. And
on the other hand, how can we fix the pressure for the cell. did i do the
right thing in the following input? (Does it means the pressure acting on
the cell after minimization =12.8 kba?)

&control
    calculation = 'vc-relax'
    restart_mode='from_scratch',
    prefix='Polyethylene',

    tstress = .true.
    tprnfor = .true.
  pseudo_dir =
'/afs/ictp.trieste.it/home/v/vdiep/espresso-2.1.3/Polyethylene/',
    outdir='/afs/ictp.trieste.it/home/v/vdiep/espresso-2.1.3/Polyethylene/'
 /
 &system
     ibrav=8,
                    celldm(1) = 13.48016706
                    celldm(2) = 0.7173398007
                    celldm(3) = 0.3609829952
    nat=12 , ntyp= 2,
    ecutwfc =40.0,
 /
 &electrons
    diagonalization='cg'
    mixing_mode = 'plain'
    mixing_beta = 0.7
    conv_thr =  1.0d-8
 /
 &ions
 ion_dynamics='damp'
 /
 &cell
 cell_dynamics='damp-w'
 press=12.85
 /


ATOMIC_SPECIES
 C  12.0107 C.pbe-van_bm.UPF
 H  1.00794 H.pbe-van_bm.UPF

ATOMIC_POSITIONS {angstrom}
           C -0.3176744885 -0.2775159117 0.6437500001
          H -0.2369597346 -1.384577396 0.6437500001
          H -1.403859394 -0.0488188374 0.6437500001
          C 0.3176744885 0.2775159117 -0.6437500001
          H 0.2369597346 1.384577396 -0.6437500001
          H 1.403859394 0.0488188374 -0.6437500001
            C 3.248975510 2.836015910 1.931250000
            H 2.162790604 2.607318836 1.931250000
            H 3.329690265 3.943077394 1.931250000
            C 3.884324490 2.280984090 0.643750000
            H 4.970509396 2.509681164 0.643750000
            H 3.803609735 1.173922606 0.643750000


K_POINTS {automatic}
 2,2,2,0,0,0

Thank you very much for your help.
Best regards,

Vinh


-------------------------------------------------
Diep Vinh Quang
C/o Diploma Program, The Abdus Salam
International Center for Theoretical Physics(ICTP),
11 Strada Costiera, 34014, Trieste,Italy.
http://www.ictp.it