Electric field effects on the performance of a candidate multipole molecular switch: a quantum computational study.

Structural and electronic responses of the organic molecule di(4-nitro-2-methylenamine phenyl) diazene a candidate molecular switch, as an active device in a nanoelectronic circuit, to the external electric fields with strengths 5 x 10(-4) - 1.8 x 10(-2) a.u. included explicitly in the Hamiltonian are studied using B3LYP/6-31G* method. This study shows that thermodynamic formation functions are not affected significantly by the applied field. Electronic spatial extent show a negligibly small change (<2%) over the studied range of the electric field strength. Calculated electric dipole moments show significant sensitivity to the external electric field, which result consequently in much stronger interactions with the electrodes (poles) of the mother nanoelectronic circuit at higher electric field strengths. Natural bond orbital atomic charges analysis shows different field effects on different atoms depending on their positions with respect to the direction of the field. The applied field increases HOMO, LUMO, and the Fermi level energies; however, decreases the HOMO-LUMO gap (HLG) values. Results of this study show that it is possible to control field-induced charge redistribution over the molecule by using push-pull effects of different substitution via their connection points to the extended pi-system. (c) 2007 Wiley Periodicals, Inc.