Programme

P.1 -- Poster, ANSWCCMS-2023

Date: Tuesday, 7 November 2023

Time: 13:00 - 14:30

Isotopic effects in thermodynamic properties of rare-gas solids

Huynh Mai Thuan (1), Nguyen Phuoc The (2,3), Ho Khac Hieu (2,3)

(1) Danang Hermann Gmeiner High School (2) Department of Environment and Natural Science, Duy Tan University, Danang Vietnam (3) Institute of Research and Development, Duy Tan University, Danang Vietnam

Isotopic effects in thermodynamic properties (including mean-square displacement, Debye-Waller factor, specific heat at constant pressure and linear thermal expansion coefficient) of rare-gas solids have been considered using the statistical moment method in statistical mechanics. This approach allows us to study these effects including the anharmonicity of lattice vibrations. We implement calculations for Ne ({20}^Ne and {22}^Ne ) and Ar ({36}^Ar và {40}^Ar) isotopes in temperature range from 0 K to the their melting temperatures using Lennard-Jones potential to describe the interaction between quantum particles. The discrepancy in thermodynamic quantities between the isotopes is believed to be attributed to the difference of atomic mass of the isotopes. Additionally, the significant difference in Debye-Waller factors between the isotopes becomes distinctly observable at low temperatures (below 15 K) and diminishes gradually at higher temperatures (above 20 K). This is explained by the disparity in the contribution of the zero-point vibrations at low temperatures and the prevalence of anharmonic effects caused by lattice vibrations at high temperatures. The favorable consistency between our findings and the available experimental data attests to the potential of statistical moment method as a novel approach for determining the thermodynamic quantities of materials.

Presenter: Ho Khac Hieu