International Science Community Association Research Journal of Recent Sciences 2277 - 2502 1 3 2012 March 2 Theoretical Studies on the Isomers of Quinazolinone by first Principles 11 18 EN Chauhan RekhaRani 1 Department of Botany, KGK PG College, Moradabad-244001, UP, INDIA Chaudhary Reema 2 Plant Physiology Laboratory, Department of Botany, Hindu College Moradabad-244001, UP, INDIA Singh Alka 3 Singh P.K. 4 Srivastava RajeshKumar 1 Physics Department, University of Lucknow, Lucknow, INDIA Narayan Vijay 2 Kumar Amarendra 3 Prasad Onkar 4 Sinha Leena 5 > Research Paper 2012 1 31 2012 March 2 The present communication is aimed at comparing the molecular structural properties, vibrational and energetic data of 2- and 4- quinazolinone, the two isomers of Quinazolinone, a biologically active hetrocyclic compound, in gas phase, due to their pharmacological activities and applications. The ground state properties of the two isomers have been calculated employing DFT/ B3LYP level of theory using the basis sets 6-311G(d), 6-311+G(d,p), 6-311++G(d,p). The dipole moment and mean polarizability are calculated to be 6.4687 Debye and 110.202/a.u. in case of 2- quinazolinone and for 4-quinazolinone these values are 1.4611 Debye and 107.663/a.u. at B3LYP/ 6-311++G(d,p) level of theory. MESP surfaces have also been drawn and compared. In order to obtain a complete description of molecular dynamics, vibrational wavenumber calculation along with the normal mode analysis, have been carried out at the DFT level. Copyright@ International Science Community Association