Multiwfn forum

aitouna

Member

Registered: 2019-10-27

Posts: 20

Transition state problem

Hi everybody,

I optimized a transition state (QST method), and the optimization finished normally (all the criteria are YES), but the imaginary frequency not correspond to breaking/forming bond. I don't know how to fix this situation.

Sincerely,
Anas Ouled aitouna

Last edited by aitouna (2019-11-08 12:14:34)

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,773

Website

Re: Transition state problem

Probably the initial guess automatically generated by QST2 is too poor.
Consider using opt(ts,calcfc,noeigen) keyword with proper initial guess of TS geometry. I always prefer opt=TS over opt=QST2, because in the case of opt=TS the initial guess is fully controllable.

aitouna

Member

Registered: 2019-10-27

Posts: 20

Re: Transition state problem

Thank you very much Professor Tian Lu.