[Pw_forum] How to calculate unoccupied states using cp.x

[Hongjun Xiang]

Dear Prof. Giannozzi,
Thank you for your reply.

I obtain correct occupied and unoccupied eigenvalues
using the following setting:
&SYSTEM
...
nbnd=4
/
&ELECTRONS
emass = 300.d0,
emass_cutoff = 2.5d0,
orthogonalization = 'ortho',
electron_dynamics = 'damp',
tcg=.true.
empty_states_nbnd=4
/

Have a good day.

Best regards,
Hongjun Xiang

=============================================================
H. J. Xiang
Postdoctoral Research Associate
National Renewable Energy Laboratory
http://www4.ncsu.edu/~hxiang/
============================================================= 


Paolo Giannozzi wrote:
> On Sep 13, 2007, at 24:41 , Hongjun Xiang wrote:
>
>   
>> It seems that when nbnd is larger than the number of the occupied  
>> states,
>> CG gives even wrongs occupied eigenvalues.
>>     
>
> before stating that eigenvalues are wrong, you should carefully verify
> that they are well converged. Eigenvalues are more sensitive than
> total energies to convergence, since the latter is a variational
> quantity (i.e. has a minimum for the ground state charge density),
> the former aren't.
>
> There is an option (I don't remember which one) that allows calculating
> empty Kohn-Sham eigenvalues in cp.x . It is described in the input
> documentation, file Doc/INPUT_CP .
>
> Paolo
> ---
> Paolo Giannozzi, Democritos and University of Udine, Italy
>
>
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