[molpro-user] Freq MRCI symmetry

Sharapa dmitriy.sharapa at fau.de
Sun Jan 11 15:55:01 GMT 2015

Dear all,

I am trying to calculate MRCI optimisations and frequencies on some 
symmetrycal systems.
For example in case of ethylene (i do not care that this is 
singlereferent system) i can make constraint optimisation with specified 
symmetry (X,Y,Z), while frequenies crashes
// Computing numerical hessian using default procedure for command MRCI//
// Symmetry elements for unique displacements: X  Y  Z //
/*/ Using no symmetry in wavefunction calculations/*/
// Running default procedure: MULTI000  MRCI//
// Recomputing wavefunction at reference geometry//
// ? Error//
// ? incorrect ldact//
// ? The problem occurs in ciinit/

while its runs normally for the same calculation without symmetry 
(result is little bit wierd, but thats also not a problem). (both attached)
The point is that removing the symmetry make calculation terribly more 
expensive - already for ethylene cost for single CI calculation rises 4 
times, for slightly bigger systems (of interest) - first iteration of CI 
calculation (even before going to Hessian block) requires 16 times more 
time and then job fails due to luck of memory or disk space. Can i do 
anything with it?

Thanks in advance,

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