https://doi.org/10.1140/epjp/s13360-025-06317-w
Regular Article
A double exponential Morse potential energy function for diatomic molecules
1
School of Science, Key Laboratory of High Performance Scientific Computation, Xihua University, 610039, Chengdu, China
2
Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, 100084, Beijing, China
a
fanzhixiang@mail.xhu.edu.cn
b
tianhongrui@163.com
Received:
5
April
2024
Accepted:
11
April
2025
Published online:
7
May
2025
In this work, we have proposed and tested a double exponential Morse (DEM) potential energy function (PEF) which describes the interatomic interactions of diatomic molecules. The DEM PEF, composed of the remedy function to the Morse PEF, is used to describe the vibrational motion for the ground electronic states of Br2 and Cl2 molecules. Comparing the Morse and DEM potential energy functions (PEFs), only three experimental spectral constants like 
for both cases are needed to be taken into account. Furthermore, the potential energy curves (PECs) and the vibrational energy levels for the ground electronic states of Br2 and Cl2 molecules are calculated by the DEM potential, Hulburt–Hirschfelder (HH) potential, Morse potential, improved multiparameter exponential-type (IMPET) potential and Huxley–Murrell (HM) potential. The results reveal that the DEM potential fits the Rydberg–Klein–Rees (RKR) data much better against other potentials, especially in the medium-long range regions. The vibrational energy levels derived from the DEM PEF align more closely with the experimental data. Moreover, the DEM potential provides opportunities for theoretical calculations of reduced molar Gibbs free energy and the molar entropy in a temperature range of 100–6000 K.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
