Isolated spherical impurity in noble gas crystals

Abstract

To explain the experimentally observed structural anomalies in diluted solid solutions of argon in krypton, we calculated the positions of atoms in a nine-layer spherical cluster of krypton with an argon atom in the center. The interaction was approximated with the Lenard–Jones potential. The substitution volume ω of an argon atom in the krypton crystal was calculated. It was shown that compared to the generally accepted estimates obtained within the nearest-neighbor approximation, the value of ω is approximately twice as small. This effect is explained by an additional repulsion of the first coordination sphere of krypton atoms arising as the krypton atoms approach each other upon their inward motion.