[molpro-user] DIATOMIC routine and harmonic potential

Lorenzo Lodi l.lodi at ucl.ac.uk
Mon Jan 20 13:18:50 GMT 2014

I think the problem is in the units. Molpro understands your input for
energies is expressed in angstroms and hartree (NOT eV).
The value given by molpro, 2720 cm-1, is correct and is equal to h2cm *
a0* 1/sqrt(uma) where
h2cm=219474.6313705 converts hartrees to cm-1
a0=0.52917721092 convertion atomic units (bohrs) to angstroms
uma=1822.8885 conversion from atomic mass units (ie Daltons) to atomic
units (ie electron masses)


Il 20/01/2014 10:25, Kucukbenli Emine ha scritto:
> Dear Molpro users and developers,
> As a new Molpro user I am experimenting with several features. Currently
> I want to understand better how to extract the spectroscopic parameters
> using "Diatomic" routine. To test the basics, I made the following table
> of bond length versus energy for a hypothetical molecule with perfectly
> harmonic potential: reduced mass of 1u, equilibrium bond length of 1.6
> angstrom, equilibrium energy of 1eV and a spring constant of 1eV/Angstrom^2:

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