[Pw_forum] Driving me nuts!

[aaron at nemo.physics.ncsu.edu]

Hi Timothy,

Just some thoughts on your job... Have you tried a more physical distance
between the two Si atoms?  It can be very difficult to optimize the
electronic wavefunction when they are almost right on top of each other.  
Also from what I understand, the procedure can be to fix the atoms,
optimize the electronic wavefunction (e-kinetic energy goes to
approximately zero) and then begin with moving the ions (in fact this 
becomes more than one input file).
Finally if you can show your output we can more correctly diagnose your 
problem(s).

I hope this helps,

Aaron

 On Tue, 16 Nov 2004, Timothy A.V. 
Teatro wrote:

> Hi. I'm really sorry to ask a question like this. I wrote this input
> file a while ago. I have been fiddling with it for a while now, and I
> can't figure out why I can't get two simple little silicon atoms to
> move! I am accustomed to using PWscf, but I am not trying to switch to
> FPMD for more accurate dynamics. But I cannot get any dynamics out of
> this thing! Even when I try putting the Si atoms very close to each
> other, where the forces should be enormous I can't get them to move.
> 
> Thanks a lot for looking at this. I'm sure I did something very silly,
> which is going to embarrass me later.
> 
> Here is a verbatim listing of the input script:
> 
> #!/bin/sh
> 
> PW_ROOT=$HOME/cpmd/FPMD
> PSEUDO=$HOME/cpmd/pseudo
> TMP_DIR=$HOME/cpmd/tmp0
> 
> if [ ! -d results ]; then 
>    mkdir  results
> fi
> cd results
> 
> rm -rf $TMP_DIR/*
> 
> cat > sih.cp1.in << EOF
> 
> &CONTROL
>   title = ' Silicon ',
>   calculation = 'cp',
>   restart_mode = 'from_scratch',
>   pseudo_dir = '$PSEUDO/',
>   outdir='$TMP_DIR/',
>   ndr = 51,
>   ndw = 51,
>   nstep  = 50,
>   iprint = 10, 
>   isave  = 100,
>   tstress = .TRUE.,
>   tprnfor = .TRUE.,
>   dt    = 5.0d0,
>   etot_conv_thr = 1.d-9,
>   ekin_conv_thr = 1.d-4,
>   prefix = 'si'
> /
> 
> &SYSTEM
>   ibrav = 1, 
>   celldm = 10.61,
>   nat  = 2,
>   ntyp = 1,
>   nbnd = 4,
>   nelec = 8,
>   ecutwfc = 8.0,
>   xc_type = 'BLYP'
> /
> 
> &ELECTRONS
>   emass = 400.d0,
>   emass_cutoff = 2.5d0,
>   orthogonalization = 'ortho',
>   ortho_eps = 5.d-8,
>   ortho_max = 15,
>   electron_dynamics = 'sd',
>   ! electron_damping = 0.3,
>   electron_velocities = 'zero',
>   electron_temperature = 'not_controlled',
> /
> 
> &IONS
>   ion_dynamics = 'verlet',
>   ion_damping = 0.2,
>   ion_radius(1) = 0.8d0,
>   ion_radius(2) = 0.8d0,
>   ion_velocities = 'zero',
>   ion_temperature = 'nose',
>   tempw = 1000,
>   fnosep = 1.2,
>   tolp=100,
>   ion_nstepe = 10
> /
> 
> &CELL
>   cell_dynamics = 'pr',
>   cell_velocities = 'zero',
>   press = 0.0d0,
> /
> 
> ATOMIC_SPECIES
>  Si  28.086  Si.vbc.UPF 4
> 
> ATOMIC_POSITIONS
> Si 0.00 0.00 0.00
> Si 0.00 0.00 0.10
> 
> K_POINTS
>  1
>  0.0 0.0 0.0 1.0
> EOF
> 
> $PW_ROOT/par2.x < sih.cp1.in > Si.md64H.out
> 
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