On the exclusion of the negative contribution to the molecular partition function

ABSTRACT

The article presents classical mechanics approach to thermodynamic properties of molecules at high temperatures which is based on a specific realisation of the idea of excluded volume and in the end avoids the use of second virial coefficient (in contrary to other approaches). The aim of this approach is to remove the negative contribution to the molecular partition function. The influence of the negative part on the partition function is investigated for the ground state of Na${}_2$ molecule. The full molecular partition functions (with bound, resonance and scattering contributions) are compared with the ones with negative contribution excluded. Additionally the applicability of the hard spheres repulsion is investigated and the comparison with an exact free (scattering) contribution is made.

GRAPHICAL ABSTRACT

KEYWORDS:

• Molecular partition function
• excluded volume
• bound states
• repulsive interaction
• hard spheres model

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Marcin Buchowiecki http://orcid.org/0000-0002-6789-9108