Input file for GaAs geometry optimization

Hi all,
can you suggest an input file to do DFT geometry optimization for GaAs? I can't get it working (something about the choice of basis set, functional). Thank you!

Hi Bert,

My trial input looks like:

Jun 2nd 9:19 am Local TimeJun 2nd 9:19 am Local TimeJun 2nd 9:19 am Local TimeJun 2nd 9:19 am Local TimeJun 2nd 9:19 am Local TimeJun 2nd 9:19 am Local Time~
title "GaAs"

geometry units angstroms
Ga 0.0 0.0 -2.5
As 0.0 0.0 2.5
end

basis
Ga library sto-3g
As library sto-3g
end

dft; direct; end

task dft optimize
Jun 2nd 9:19 am Local TimeJun 2nd 9:19 am Local TimeJun 2nd 9:19 am Local TimeJun 2nd 9:19 am Local TimeJun 2nd 9:19 am Local Time192.122.131.20


The goal is to optimize accurately the GaAs structure (using quality DFT functional). Either PW or Gaussian (any would do,
or as required by accuracy goal).

Hi Bert and Niri,

thanks for your quick replays. I reply to each below in detail. Additionally, do you know any way in NWChem to access 1) the band occupation numbers (ie, to change them at will) and 2) to calculate dipole transition moments (ie, <km|x,y,z|k'n> or momentum operator transitions)? Even to have the wave functions numerically could help by doing the dipole elements with quadrature (though not so accurately).

For Bert:
I went to 2 Angstr for the bond length. I tried some aug-cc-pvdz. Not much success. Could you suggest a suitable basis set for GaAs? At this point, I would be happy to see a converged calculation (ground state energy) at a given bond length (say 2 Angstrom).

For Niri:
A molecular calculation is wanted. As you can see above, I am missing some good basis set for GaAs. Basically, i would like to see a converged energy calculation at fixed bond length.

Thank you!

Thank you. For the PW approach, I encounter some difficulties with running the script. I put below the file for the band structure (inspired from the diamond example). At some points, it crashes

"0:0:cpsi_data_alloc: out of heap memory:: 0 ..."

Jun 13th 7:41 am Local TimeJun 13th 7:41 am Local Time192.122.131.20
title "GaAs"

permanent_dir ./

start GaAs

memory 3000 mb

geometry center noautosym noautoz print

 system crystal 

   lat_a 5.4d0

   lat_b 5.4d0 

   lat_c 5.4d0 

   alpha 90.0d0 

   beta  90.0d0 

   gamma 90.0d0 

 end

Ga  0.00000d0  0.00000d0  0.00000d0

As  0.25000d0  0.25000d0  0.25000d0

end

nwpw

 ewald_rcut 3.0

 ewald_ncut 8    #The default value of 1 needs to be increased

 lmbfgs

 xc pbe96

 monkhorst-pack 9 9 9

end

task band energy

nwpw

  virtual 16

  brillouin_zone

    zone_name fccpath

    path fcc l gamma x w k gamma

  end

  zone_structure_name fccpath

end

task band structure


Jun 13th 7:41 am Local TimeJun 13th 7:41 am Local Time192.122.131.20