Premium
The Analysis of Rydberg Potential and van der Waals Interactions in Alkali Halides
Author(s) -
Gupta V. P.,
Sipani S. K.
Publication year - 1990
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221610112
Subject(s) - van der waals force , halide , van der waals radius , alkali metal , rydberg formula , thermodynamics , order (exchange) , physics , chemistry , isothermal process , atomic physics , quantum mechanics , molecule , inorganic chemistry , ion , finance , economics , ionization
The short range Rydberg potential which assumes an attractive term along with the frequently used repulsive term for short range interaction is employed to calculate the transverse optic mode Grüneisen parameter (γ TO ), longitudinal optic mode Grüneisen parameter (γ LO ), Grüneisen parameter (γ), mode Grüneisen parameter ( q ), first and second order pressure derivatives of isothermal bulk modulus \documentclass{article}\pagestyle{empty}\begin{document}$\left({\frac{{{\rm dB}_T }}{{{\rm d}T}}{\rm and}\,\frac{{{\rm d}^{\rm 2} B_T }}{{{\rm d}P^2 }}} \right)$\end{document} , and volume expansion coefficient (β) for NaCl‐ and CsCl‐structure alkali halides taking into account the three different sets of van der Waals coefficients and three different theories namely, the Slater theory, Dugdale and McDonald (DM) theory, and free volume (FV) theory. It is observed that the results obtained from DM theory using the values of van der Waals coefficients from Shanker and Rajoria are in good agreement with experiment. The potential has further been extended to take into account the second neighbour and three body contributions. The inclusion of second neighbour and three body interactions improves the results satisfactorily.