Structure and bonding in M-X-M systems (M=Li, Na and K; X=O, S): Effects of charge-transfer

Issue title: Alkali Metal Clusters

Guest editors: G. Maroulisx and P. Calaminiciy

Article type: Research Article

Authors: Mohan, P.J. | Datta, Ayan | Pati, Swapan K.^{; *}

Affiliations: Theoretical Sciences Unit, Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore-560064, India | [x] Department of Chemistry, University of Patras, Greece | [y] Departamento de Quimica, CINVESTAV, Centro De Investigacion Y De Estudios Avanzados, Av. Instituto Politecnico Nacional, 2508, A.P. 14-740, Mexico, D.F. 07000, Mexico

Correspondence: [*] Corresponding author. E-mail: pati@jncasr.ac.in.

Abstract: Structure and bonding for a series of oxo-bridged and sulphur bridged alkali-metal centers (M-X-M: Li, Na and K; X=O, S) are studied for various M-X-M angles. The structures for these charge-transfer systems are compared with H-X-H. These charge- transfer systems show bonding and structures that are distinctively different from the covalent H-X-H molecules. The singlet-triplet gap for all of these molecules are positive suggesting the stabilization of the spin-paired configuration instead of the paramagnetic state. The variation in the exchange-coupling constant (J) with the change in M-X-M angle suggest that the singlet- triplet gap for these systems can be reduced through stabilization of geometries with M-X-M angles differing from the ground state geometries. Strategies are proposed for reducing the singlet-triplet gaps in these systems by confining them inside fullerenes.

Keywords: Alkali metal chalogenides, exchange coupling (J), broken symmetry calculations, Goodenough-rules

DOI: 10.3233/JCM-2007-75-613

Journal: Journal of Computational Methods in Sciences and Engineering, vol. 7, no. 5-6, pp. 489-494, 2007