How to calculate polarizability
Clicked A Few Times
2:56:29 AM PDT - Thu, Oct 31st 2013
Dear NWChem friends,

In order to obtain refractive index of a compound, I want to calculate polarizability
tensor at a specified frequency (ex. 589.3nm=0.077315 au ) then I made the input file
as shown below. But, an error message has appeared. Could you tell me what is wrong
with this input file.

echo
start C6H6-POL
title "Polarizability of Benzene"

geometry units angstrom
C -1.209387 -0.698222 0.000000
C -1.209427 0.698262 0.000000
H -2.150069 -1.241320 0.000000
C -0.000014 1.396475 0.000000
H -2.150108 1.241358 0.000000
H -0.000012 2.482676 0.000000
C 1.209387 0.698222 0.000000
H 2.150068 1.241320 0.000000
C 1.209426 -0.698262 0.000000
H 2.150107 -1.241358 0.000000
C 0.000013 -1.396474 0.000000
H 0.000011 -2.482675 0.000000
end
DFT 
 XC  b3lyp 

 MULT 1
END
basis
C  library 6-31G*

H  library 6-31G*
end
TDDFT
RPA
end
PROPERTY
response 1 0.077315

velocity

dipole
end
task tddft energy


Error message 
------------------------------------------------------------------------

tddft_init: non-Abelian symmetry not permitted        0

------------------------------------------------------------------------

There is an error related to the specified geometry

------------------------------------------------------------------------

Forum Vet
9:32:48 AM PDT - Thu, Oct 31st 2013
use C2h point group
NWfmohri
The error message is telling you that the C6h point group that your molecule belongs to is non-abelian,
therefore the TDDFT code -- that exploits abelian symmetry -- cannot cope with it.
The fix is to choose an abelian point group that is a subset of C6h.
I choose C2h, and this requires to add the line symmetry c2h in the geometry input section,
as shown below


geometry units angstrom
symmetry c2h
C -1.209387 -0.698222 0.000000
C -1.209427 0.698262 0.000000
H -2.150069 -1.241320 0.000000
C -0.000014 1.396475 0.000000
H -2.150108 1.241358 0.000000
H -0.000012 2.482676 0.000000
C 1.209387 0.698222 0.000000
H 2.150068 1.241320 0.000000
C 1.209426 -0.698262 0.000000
H 2.150107 -1.241358 0.000000
C 0.000013 -1.396474 0.000000
H 0.000011 -2.482675 0.000000
end

Clicked A Few Times
7:02:07 PM PDT - Fri, Nov 1st 2013
Thank you for four reply. I will try C2h symmetry.


Forum >> NWChem's corner >> General Topics