Default atomic masses and their rationale

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Default atomic masses and their rationale

Postby agtonner » Fri Feb 22, 2019 3:55 pm


when looking at the default atomic masses used in VASP I saw that e.g. H is defined as exactly 1 amu when it should be 1.008 (
This might not look like much but it changes the frequency of vibrations by 10-30 wavenumbers.

I assume that the masses are all relative to 1^H instead of 1/12 12^C ?

Is there a reason those masses are chosen for VASP? Is there a reference for how these were obtained? Should it be changed to reach parity with IUPAC?

Thank you for your assistance.

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