[Pw_forum] geometry optiiztion of metal clusters

[Wohlwend, Jennifer L CTR USAF AFMC AFRL/RXBT]

I'm trying to perform geometry optimization of some clusters and they are
running extremely slow. For example a TiO2 anatase cluster of only 12 atoms
has completed only a few self-consistent iterations after ~3 hours. I know I
must be doing something wrong but I've not been able to spot it yet. For the
TiO2 system, my input is as follows:
&CONTROL
                       title = Ti_relax ,
                 calculation = 'relax' ,
                restart_mode = 'restart' ,
                      outdir = './' ,
                      wfcdir = './' ,
                  pseudo_dir = '/hafs15/jen7182/espresso/pseudo/' ,
                 lkpoint_dir = .true. ,
               etot_conv_thr = 1.0D-6 ,
               forc_conv_thr = 1.0D-6 ,
                       nstep = 120 ,
                     tstress = .true. ,
                     tprnfor = .true. ,
                      lberry = .false. ,
 /
 &SYSTEM
                       ibrav = 1,
                   celldm(1) = 50.0000000,
                         nat = 12,
                        ntyp = 2,
                     ecutwfc = 55 ,
                     ecutrho = 500 ,
                 occupations = 'smearing' ,
                     degauss = 0.02D0 ,
                    smearing = 'methfessel-paxton' ,
 /
 &ELECTRONS
                    conv_thr = 1.D-8 ,
/
 &IONS
                ion_dynamics = 'bfgs' ,
  pot_extrapolation = "second_order",
  wfc_extrapolation = "second_order",
 /
ATOMIC_SPECIES
    Ti   47.87000  Ti.pw91-nsp-van.UPF
15.99960  O.pw91-van_ak.UPF
ATOMIC_POSITIONS
Ti      0.019646921155  -0.032104589149 0.072982942110
Ti      -0.053021298671 0.015633269982  0.132549510485
Ti      0.057125188587  0.058771047647  0.164020158511
Ti      0.110388124153  0.105884441223  0.244068937730
O       -0.023076017443 -0.044401500581 0.131365372724
O       0.035579202732  -0.080351647885 0.029496520030
O       -0.037172544158 0.018329722652  0.066778689936
O       0.057973293750  0.014983392566  0.111654528302
O       -0.014261394120 0.057693305910  0.168967680139
O       0.116729745829  0.144794684381  0.294813978638
O       0.083638150059  0.040575025164  0.225871612978
O       0.091668444256  0.117426432280  0.178170567176
K_POINTS automatic
4 4 4   1 1 1
Any help would be greatly appreciated!!
Thank you!
Jennifer
Jennifer L. Wohlwend, Ph.D.
Thermal Sciences and Materials Branch
Materials and Manufacturing Directorate
Air Force Research Laboratory
2941 Hobson Way B654 R015
Wright Patterson Air Force Base, OH 45433-7750
Ctr: Universal Technology Corporation
Phone: (937) 656-4918
Email: jennifer.wohlwend.ctr at wpafb.af.mil 


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