An evaluation of the thermal properties of H₂ and O₂ on the basis of ab initio calculations for their intermolecular interactions

Abstract

We have calculated the potential energy surfaces for the singlet state of H₂–H₂ and for the quintet state of using the coupled-cluster theory with singles, doubles and perturbative triple excitations [CCSD(T)] and an aug-cc-pVQZ basis set. Resulting interaction potentials were expanded in spherical harmonics, separating the radial and the angular dependencies to obtain analytical expressions. Monte-Carlo simulations for the NVT ensemble were performed to evaluate pressures and heat capacities of dense H₂ and O₂ fluids. The results were compared with the available experimental data in NIST thermodynamic database.

Keywords:

• ab initio potential
• NVT Monte Carlo simulation
• equation of state
• hydrogen
• oxygen

Acknowledgements

We greatly appreciate Dr M. Bartolomei (Instituto de Fi'sica Funndamental, CSIC) for providing us his 29-term expansion coefficients for O₂–O₂ potential.

Notes

1. Email: [email protected]

2. Email: [email protected]

Additional information

Notes on contributors

Mitsuo Koshi

1

Kazuya Shimizu

2