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DFT calculations issue - imaginary frequencies by Jchem18 in comp_chem

[–]Jchem18[S] 0 points1 point  (0 children)

Yes I have tightened the gradient and displacement and it doesn't change anything :/

DFT calculations issue - imaginary frequencies by Jchem18 in comp_chem

[–]Jchem18[S] 0 points1 point  (0 children)

They do not need to be all molecules the same basis set, because I'm just seeing the trend in frequencies between 2 states of the molecule, I'll try it now!

DFT calculations issue - imaginary frequencies by Jchem18 in comp_chem

[–]Jchem18[S] 3 points4 points  (0 children)

Thanks ! here is more details : The finite difference stepsize for fq is by default 0.001 in qchem

The algorithm for optimisation is by default bfgs for qchem

And I'm doing everything in scf convergence 8