test example of SiC optimization
Just Got Here
12:32:32 PM PDT - Thu, May 2nd 2013
Hi,

When I tried to run the example "Optimizing a unit cell and geometry for Silicon-Carbide", first I got an error message to complain the lack of memory. After I increased it, the optimization converged, and got the following information


Lattice Parameters 
     ------------------ 



     lattice vectors in a.u. (scale by  1.000000000 to convert to a.u.)



     a1=<   8.646  -0.000   0.000 >

     a2=<  -0.000   8.645  -0.000 >

     a3=<  -0.000   0.000   8.127 >

     a=       8.646 b=      8.645 c=       8.127

     alpha=  90.000 beta=  90.000 gamma=  90.000

     omega=   607.4

My question is why the norm of a3 is not the same as the norm of a1. How can I force the optimization to keep the ratios between the norms of a1, a2, and a3 constant? In other words, I would like to optimization process to scale a1, a2, a3 by the same factor.

Other questions:

1. Where can I find all possible options for different directives?
  "set includelattice .true." only apprars in an example input file, but not in the section of "http://nwchemgit.github.io/index.php/Release61:Top-level#SET"

other examples: set nwpw:stress_numerical .true. #currently only numerical stresses 

                          set nwpw:psi_nolattice .true. # turns of unit cell checking for wavefunctions



Is there any list to tell users that those parameter can be set by "set nwpw:$$" for nwpw?

2. Where can I find the refence for "task band"? I can't find any relevant reference from documentation or the paper "NWChem: A comprehensive and scalable open-source solution for large scale molecular simulations"

3. I have used LAMMPS package. The documentation of LAMMPS is pretty easy to follow. Would you mind to take a look and revise the documentation which can include references and default settings?

Thank you in advance.

Dongsheng

Gets Around
9:14:19 AM PDT - Sat, May 4th 2013
http://nwchemgit.github.io/index.php/Release61:Plane-Wave_Density_Functional_Theory#Unit_Cel...

The following input seems to work for me for SiC

title "SiC 8 atom cubic cell - geometry and unit cell optimization"
echo
permanent_dir ./perm
scratch_dir ./perm
start diamond
memory 950 mb
          • Enter the geometry using fractional coordinates ****
geometry center noautosym noautoz print 
 system crystal 

   lat_a 4.00d0 

   lat_b 4.00d0 

   lat_c 4.00d0 

   alpha 90.0d0 

   beta  90.0d0 

   gamma 90.0d0 

 end

 Si -0.50000d0 -0.50000d0 -0.50000d0

 Si  0.00000d0  0.00000d0 -0.50000d0

 Si  0.00000d0 -0.50000d0  0.00000d0

 Si -0.50000d0  0.00000d0  0.00000d0

 C -0.25000d0 -0.25000d0 -0.25000d0

 C  0.25000d0  0.25000d0 -0.25000d0

 C  0.25000d0 -0.25000d0  0.25000d0

 C -0.25000d0  0.25000d0  0.25000d0
end

set nwpw:kbpp_ray .true.
set nwpw:kbpp_filter .true.
nwpw 
 ewald_rcut 3.0

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

 lmbfgs

 xc pbe96
end
driver 
 clear 

 maxiter 40
end

set nwpw:cif_filename sic.opt # create a CIF file containing optimization history
set includestress .true. # this option tells driver to optimize the unit cell
task pspw optimize ignore


nwpw
  monkhorst-pack 2 2 2
end
task band optimize ignore


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