Molcas Forum

Anugraha

Member

Registered: 2025-12-17

Posts: 22

Missing total frequencies after MP2 optimization

Hello OpenMolcas developers,

I performed a ground-state MP2 geometry optimization followed by a frequency calculation for a system consisting of 19 atoms.

& Gateway 
 coord = coord_bef_MP2_opt.xyz
 Group = z
 Basis = ANO-RCC-VDZP
>>> Export MOLCAS_MAXITER =2000
>>> Do while 
& SEWARD 
 cholesky 
& SCF 
& MBPT2 
>>> Enddo 
& MCKINLEY
& Grid_it
 All 

The geometry optimization converged successfully, and the frequency calculation also terminated . However, I observe only 35 vibrational frequencies in the log and .freq.Molden file, whereas I expect 57 frequencies.

Any guidance on how to diagnose and resolve this issue would be greatly appreciated.

Thank you
Anugraha

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,204

Re: Missing total frequencies after MP2 optimization

You did the calculation with symmetry constraints (Group = z), so I guess you get only the symmetric frequencies.