[CPMD-list] How to get to HOMO&LUMO information

[Axel Kohlmeyer]

On Sat, 12 Nov 2005, Yang Zhenyu wrote:

YZ> 
YZ> Dear Apsi
YZ> 
YZ> 	Thanks very much for your detail reply!
YZ>     This is really what I want.
YZ>     And I also want to know how to use cpmd2cube to write the HOMO and LUMO into cube files.
YZ>  Something like" cpmd2cube.x -o file-homo -dens *.*" . What options should be given to cpmd2cube.


what do you need to know, that is not already in the README file???

a few small remarks on to of apsi's mail:

- the reason for having to run the kohn-sham energies run is, that you 
  need to diagonalize the kohn-sham matrix. if you already are using
  a diagonalization scheme, to optimize the wavefunction, this is not
  needed for obvious reasons. a 'normal' cpmd wavefunction does not
  include unoccupied states and enforces only orthogonality.

- when you do the properties run, you have to make sure, that the number
  of states in the input matches the number of states of the restart.

- i'd recommend just using the RHOOUT BANDS option when doing the 
  kohn sham energies run (or together with the wavefunction optimization
  when doing a diagonalization). the current cpmd2cube has all features 
  of the properties output and then some more...   note that if you give 
  the orbital numbers, that you'll get the _density_ (i.e. |psi^2| 
  hence you need to use the -dens or -rho flag with cpmd2cube). if you 
  give the equivalent _negative_ number, you'll get the wavefunction 
  (to be converted with -wave or -psi). have a look at the -trim flag.
  it can save a lot of memory and speed up handling and visualizing a 
  large number of cube files enormously.

- you should be careful not to overinterpret these orbitals. as you
  you are using pseudopotentials, the LUMOs can only be computed with
  respect to the (occupied) valence orbitals. the LUMO and LUMO+1 are
  usually pretty close to those of an all-electron calculation, though.

you can find examples of both methods at:

http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/cpmd-tutor/part5.html#chap6_sect1

and

http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/cpmd-vmd/part5.html#chap7

regards,
     axel.

YZ> 
YZ> 
YZ> 
YZ> ¡¡¡¡¡¡¡¡¡¡¡¡¡¡
YZ> ¡¡Best Regards
YZ> 
YZ> ¡¡Yang Zhenyu				
YZ>   State Key Laboratory of Nonlinear Mechanics (LNM)
YZ>   Institute of Mechanics, Chinese Academy of Sciences
YZ>   No.15 Beisihuanxi Road
YZ>   Beijing 100080, P. R. China
YZ>   FAX: 010-62579511
YZ> ¡¡yangzy at lnm.imech.ac.cn
YZ> ¡¡2005-11-12
YZ> 
YZ> 
YZ> 
YZ> _______________________________________________
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YZ> CPMD-list at cpmd.org
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YZ> 

-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
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