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anandojha / qmmmrebind

Quantum Mechanics – Molecular Mechanics ( QMMM ) forcefield Reparamaterisation of the Binding site for the receptor-ligand complexes
MIT License
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Vibrational scaling factor #1

Closed lvotapka closed 3 years ago

lvotapka commented 3 years ago

https://github.com/anandojha/qmmmrebind/blob/e9dab0ba0d0a643f15aa16fc1915af7965616473/qmmmrebind/parameterize.py#L433

What is the purpose of the vibrational scaling factor? And what quantity does it scale - the vibrational energies? The vibrational frequencies?

anandojha commented 3 years ago

The vibrational scaling factor is a constant that accounts for anharmonicity and inaccuracies in the level of theory used. It scales the frequencies according to the level of the theory used. These frequencies are then used to calculate the bond and angle constants from the hessian matrix. It can be set to one if a scaling factor is not wanted. For detailed information about the vibrational scaling factors and how it is obtained, we can refer to the following link : https://cccbdb.nist.gov/vibscalejust.asp

lvotapka commented 3 years ago

Ah thank you, @anandojha, that makes sense.