Theoretical study of structural phase transition in a RbMnCl3 crystal by the Kim-Gordon method

Autor:	V. Yu. Kazimirov, Mikhail B. Smirnov
Rok vydání:	2003
Předmět:	Physics Condensed matter physics General Chemistry Condensed Matter Physics Crystal Polyhedron Computational chemistry Irreducible representation Lattice (order) Saddle point Perpendicular General Materials Science Eigenvalues and eigenvectors Monoclinic crystal system
Zdroj:	Crystallography Reports. 48:435-442
ISSN:	1562-689X 1063-7745
DOI:	10.1134/1.1578128
Popis:	Symmetry analysis of the low-temperature phase of RbMnCl3 crystals with the monoclinic axis perpendicular to the sixfold axis of the high-temperature phase showed that its space group is either C2h3 or C2h6 The distribution of normal vibrations over the irreducible representations of the high-temperature phase is refined, and the symmetry relationships for normal vibrations of all possible low-temperature phases are tabulated. The model of the potential function of the crystal is obtained by the nonempirical Kim-Gordon method. This model allows one to establish the existence of the saddle point of the potential surface and several harmonically unstable modes corresponding to correlated rotations of rigid MnCl6 and Mn2Cl9 polyhedra. The absolute energy minimum is determined by deforming the lattice along the eigenvector of the E1g mode within the sp. gr.. C2h6.
Databáze:	OpenAIRE
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