Hello everyone! I would like to know the way of choosing or determining the scaling factors for calculated vibrational frequencies so as to get a close similarity with the experimental IR for an organic molecule that is optimized in the levels HF/6-311++G(d,p), B3LYP/6-311++G(d,p) and HSEH1PBE/6-311++G(d,p) exclusively.
Is the scaling factors dependent on the method and basis set used?
Also, what is a dual scaling factor (and single scaling factor, if any) and where should those be used? If possible, please share articles related to the query. Thank you in advance.
There is no foolproof method to scale the vibrational frequencies which will match theoretical to experimental. As the vibrational frequencies which we are getting in gaussian are harmonic in nature but the real experimental ones are anharmonic. But the trends will be same throughout.'
Yes, they depend on the method and basis set used. My suggestion is to use the standard method and state of art basis set to get the minimum error. Also, you have to multiply it will a scaling constant to get the value close to experimental ones.
For considering anharmonic corrections, i.e. computing higher-order derivatives. use, "Anharmonic" keyword into the route section
Hope I have answered your question.
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