Theoretical Investigation of Magnetic and Conducting Properties of Substituted Silicon Chains. I. Hydrogen and Oxo-Verdazyl Ligands

Abstract

In this work, we investigate the magnetic and conducting properties of polysilene chains attached to the stable free radical oxo-Verdazyl (o-VER) via C-linkage, by using quantum chemical and solid state methods. Calculations are first carried out on 39 possible monomers in their triplet and broken symmetry states following the density functional methodology UB3LYP and using Gaussian 03 and 09 codes. The magnetic exchange coupling constant (J) is calculated for each species. Here, the magnetic exchange coupling constant J equals the negative of the ratio of the energy difference and difference between the low-spin and the high-spin ground states, in accordance with the Heisenberg spin exchange Hamiltonian. Geometry is optimized using the 6-31G(d) basis set. Single-point calculations on the triplet and broken symmetry states are performed with the optimized geometries and 6-311G(d,p) basis set. Calculations on three series of molecules of interest are finally done by employing the 6-311++G(d,p) basis s...