[Pw_forum] structural relaxation for a M-M-M system
Xunlei Ding
ding at sissa.it
Sat Jun 9 15:32:59 CEST 2007
Dear Sen,
What the directions of the forces, mostly in XY plane or in Z direction?
Are you using slab model? Where you get the number celldm(1) = 16.0?
Please give more information.
Yours sincerely,
Ding
Sen wrote:
>Dear all,
> After a lot of trials, I am, however, not yet successful in
>optimizing a metal-molecule-metal system as the forces are coming
>like this:
>.........
> Total force = 0.095460 Total SCF correction = 0.000604
> Total force = 0.082488 Total SCF correction = 0.000306
> Total force = 0.046922 Total SCF correction = 0.000911
> Total force = 0.056506 Total SCF correction = 0.000344
> Total force = 0.054621 Total SCF correction = 0.000626
> Total force = 0.065249 Total SCF correction = 0.000466
> Total force = 0.083905 Total SCF correction = 0.000689
> Total force = 0.079088 Total SCF correction = 0.000242
> Total force = 0.062822 Total SCF correction = 0.000331
> Total force = 0.042837 Total SCF correction = 0.000466
> Total force = 0.043863 Total SCF correction = 0.000608
> Total force = 0.060127 Total SCF correction = 0.000548
> Total force = 0.056791 Total SCF correction = 0.000600
> Total force = 0.055846 Total SCF correction = 0.000490
> Total force = 0.048528 Total SCF correction = 0.000801
> Total force = 0.035071 Total SCF correction = 0.000413
> Total force = 0.032172 Total SCF correction = 0.000433
> Total force = 0.039041 Total SCF correction = 0.000416
> Total force = 0.044582 Total SCF correction = 0.000545
> Total force = 0.046444 Total SCF correction = 0.000524
> Total force = 0.054854 Total SCF correction = 0.000818
> Total force = 0.063710 Total SCF correction = 0.000484
> Total force = 0.062717 Total SCF correction = 0.000626
> Total force = 0.065163 Total SCF correction = 0.000812
> Total force = 0.075249 Total SCF correction = 0.001036
> Total force = 0.088846 Total SCF correction = 0.000643
> Total force = 0.105373 Total SCF correction = 0.000338
> Total force = 0.120634 Total SCF correction = 0.000572
> Total force = 0.126982 Total SCF correction = 0.000283
> Total force = 0.113945 Total SCF correction = 0.000450
> Total force = 0.108384 Total SCF correction = 0.000297
> Total force = 0.099096 Total SCF correction = 0.000580
> Total force = 0.077881 Total SCF correction = 0.000668
> Total force = 0.095374 Total SCF correction = 0.000452
>
> while the stress is the following:
> total stress (Ry/bohr**3) (kbar) P=
>34.70
> total stress (Ry/bohr**3) (kbar) P=
>34.72
> total stress (Ry/bohr**3) (kbar) P=
>35.27
> total stress (Ry/bohr**3) (kbar) P=
>35.66
> total stress (Ry/bohr**3) (kbar) P=
>35.07
> total stress (Ry/bohr**3) (kbar) P=
>33.99
> total stress (Ry/bohr**3) (kbar) P=
>32.67
> total stress (Ry/bohr**3) (kbar) P=
>31.43
> total stress (Ry/bohr**3) (kbar) P=
>31.16
> total stress (Ry/bohr**3) (kbar) P=
>31.69
> total stress (Ry/bohr**3) (kbar) P=
>32.41
> total stress (Ry/bohr**3) (kbar) P=
>33.54
> total stress (Ry/bohr**3) (kbar) P=
>33.84
> total stress (Ry/bohr**3) (kbar) P=
>34.53
> total stress (Ry/bohr**3) (kbar) P=
>34.35
> total stress (Ry/bohr**3) (kbar) P=
>34.06
> total stress (Ry/bohr**3) (kbar) P=
>33.97
> total stress (Ry/bohr**3) (kbar) P=
>34.12
> total stress (Ry/bohr**3) (kbar) P=
>34.65
> total stress (Ry/bohr**3) (kbar) P=
>34.86
> total stress (Ry/bohr**3) (kbar) P=
>34.38
> total stress (Ry/bohr**3) (kbar) P=
>33.60
> total stress (Ry/bohr**3) (kbar) P=
>32.83
> total stress (Ry/bohr**3) (kbar) P=
>32.23
> total stress (Ry/bohr**3) (kbar) P=
>32.38
> total stress (Ry/bohr**3) (kbar) P=
>32.16
> total stress (Ry/bohr**3) (kbar) P=
>32.24
> total stress (Ry/bohr**3) (kbar) P=
>32.34
> total stress (Ry/bohr**3) (kbar) P=
>32.88
> total stress (Ry/bohr**3) (kbar) P=
>34.00
> total stress (Ry/bohr**3) (kbar) P=
>33.58
> total stress (Ry/bohr**3) (kbar) P=
>33.10
> total stress (Ry/bohr**3) (kbar) P=
>32.30
> total stress (Ry/bohr**3) (kbar) P=
>31.50
>
>I start my calculations with the following input file:
>&CONTROL
> calculation = "relax",
> tstress = .TRUE.,
> tprnfor = .TRUE.,
> dt= 20,
> outdir = "/work1/tmp",
> prefix = "6r_md",
> pseudo_dir = "/work1/pwscf/newwork1/pseudo",
>/
>&SYSTEM
> nosym = .TRUE.,
> ibrav = 6,
> celldm(1) = 16.0,
> celldm(3) = 6.7,
> nat = 108,
> ntyp = 4,
> ecutwfc = 25.0,
> ecutrho = 200.0 ,
> occupations = "smearing",
> degauss = 0.01,
> smearing = "gauss",
>/
>&ELECTRONS
> conv_thr = 1.e-7,
> mixing_beta = 0.1,
>/
>&IONS
> ion_dynamics = "damp",
> pot_extrapolation = "second_order",
> wfc_extrapolation = "second_order",
>ATOMIC_SPECIES
>Au 1.00 Au.pbe-van_ak.UPF
>S 1.00 S.pbe-van_ak.UPF
>C 1.00 C.pbe-van_ak.UPF
>H 1.00 H.pbe-van_ak.UPF
>ATOMIC_POSITIONS {bohr}
>Au 0.000000000 -4.965200000 0.000000000 0 0 0
>Au -4.319724000 -2.482600000 0.000000000 0 0 0
>Au -4.319724000 2.482600000 0.000000000 0 0 0
>.................
>Au -2.774561616 0.031062380 28.596765964 1 1 1
>Au 0.041848351 -0.082778583 32.636501628 1 1 1
>Au -0.028301935 1.263362498 37.301572656 1 1 1
>.................
>C 0.003014820 -0.792207427 45.903314488 1 1 1
>H -1.656592433 -2.071574048 45.925688702 1 1 1
>H 1.659769150 -2.074993963 45.925343414 1 1 1
>.................
>Au 0.002439106 5.120271920 81.897457381 1 1 1
>Au -4.361967945 2.134818447 81.462315449 1 1 1
>Au -5.204105949 -3.027358489 81.522909929 1 1 1
>.................
>Au -4.319724000 2.482600000 98.968460000 0 0 0
>Au -4.319724000 -2.482600000 98.968460000 0 0 0
>Au 0.000000000 -4.965200000 98.968460000 0 0 0
>K_POINTS {Gamma}
>
>I tried with vc-relax as well but could not improve it much. In another
>system, I came across the following forces:
> Total force = 0.506859 Total SCF correction = 0.000423
> Total force = 0.501602 Total SCF correction = 0.000666
> Total force = 0.504022 Total SCF correction = 0.000468
> Total force = 0.515807 Total SCF correction = 0.000445
> Total force = 0.531093 Total SCF correction = 0.000497
> Total force = 0.546169 Total SCF correction = 0.000294
> Total force = 0.565997 Total SCF correction = 0.000298
> Total force = 0.594369 Total SCF correction = 0.000437
> Total force = 0.628540 Total SCF correction = 0.000323
> Total force = 0.652224 Total SCF correction = 0.000388
> Total force = 0.636638 Total SCF correction = 0.000299
> Total force = 0.558604 Total SCF correction = 0.000572
> Total force = 0.441045 Total SCF correction = 0.000310
> Total force = 0.331614 Total SCF correction = 0.000424
> Total force = 0.230756 Total SCF correction = 0.000319
> Total force = 0.188110 Total SCF correction = 0.000422
> Total force = 0.160244 Total SCF correction = 0.000236
> Total force = 0.145254 Total SCF correction = 0.000270
> Total force = 0.139637 Total SCF correction = 0.000262
> Total force = 0.125084 Total SCF correction = 0.000424
> Total force = 0.150679 Total SCF correction = 0.000854
> Total force = 0.167059 Total SCF correction = 0.000294
> Total force = 0.172462 Total SCF correction = 0.000478
> Total force = 0.179529 Total SCF correction = 0.000434
> Total force = 0.187906 Total SCF correction = 0.000499
> Total force = 0.191868 Total SCF correction = 0.000428
> Total force = 0.188061 Total SCF correction = 0.000504
> Total force = 0.175147 Total SCF correction = 0.000272
> Total force = 0.159927 Total SCF correction = 0.000273
> Total force = 0.161611 Total SCF correction = 0.000373
> Total force = 0.208462 Total SCF correction = 0.000460
> Total force = 0.280821 Total SCF correction = 0.000192
> Total force = 0.353126 Total SCF correction = 0.000699
> Total force = 0.420761 Total SCF correction = 0.000602
> Total force = 0.486584 Total SCF correction = 0.000230
> Total force = 0.550967 Total SCF correction = 0.000360
> Total force = 0.606887 Total SCF correction = 0.000672
> Total force = 0.640920 Total SCF correction = 0.000602
> Total force = 0.632764 Total SCF correction = 0.000467
> Total force = 0.559615 Total SCF correction = 0.000506
> Total force = 0.526823 Total SCF correction = 0.000464
> Total force = 0.503575 Total SCF correction = 0.000432
>.........
>Could you please suggest me as to how I could get the "Total force"
>something like 0.001 or of that sort?
>Best regards,
>Sen
>
>
>
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