[molpro-user] Linear Molecules and MP2 Frequnecies
a.simperler at imperial.ac.uk
Thu Mar 13 12:24:45 GMT 2014
Dear fellow-users and Experts
I am working on a user-question I cannot resolve.
I tried converting into z-matrix, various Orient options etc.
The molecule is H-Br-Ar and is linear and being C*V MOLPRO picks up
correctly the largest Abelian subgroup, c2v all goes well for HF and MP2 single points but once it comes to Frequencies we get a complaint that x cannot be imposed, and noorient is on which I thought was switched of by Orient to start with.
We are using Molpro2012.1 btw
So my user tried:
***, some title
H 0.0000000000 0.0000000000 -2.8437425492
Be 0.0000000000 0.0000000000 -1.5482621834
Ar 0.0000000000 0.0000000000 0.4210358303
I personally tried a Z-Matrix approach:
***, H+BeAr aug-cc-pCVQZ CCSD(T) single point calculation at
QCISD/aVQZ geometry !
Be , H , rhbe
Ar , Be , rbear , H , 180
and I ended up with:
Computing numerical hessian using default procedure for command RMP2
Symmetry elements for unique displacements: X Y
Using no symmetry in wavefunction calculations
Running default procedure: RHF-SCF000 RMP2
Numerically approximating hessian using central energy differences
Task list generated. Total number of displacements: 24
Attempt to include non-existent symmetry X Because of noorient
option, program will not align to your requested symmetry elements
Try again with different symmetry request This error can also happen
in geometry optimizations that specify
symmetry-breaking internal coordinates in terms of active variables
User-specified symmetry elements: X,Y Symmetry elements: Y ? Error
? Symmetry error ? The problem occurs in zmatrix.f:zmat_evaluate
I am very puzzled because I don't know where the noorient comes from as we specify Orient in our inputs.
Is it something trivial we missed? Then I apologize kindly in advance.
Dr Alexandra Simperler FHEA
Software Sustainability Institute Fellow 2014
Department of Chemistry
Imperial College London
London SW7 2AZ
Tel: +44 (0)20 759 41220
Email: a.simperler at imperial.ac.uk
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