Theoretical investigation of the linear and second-order nonlinear susceptibilities of the 3-methyl-4-nitropyridine-1-oxyde (POM) crystal

Semiempirical quantum chemistry techniques were used for the study of linear and second-order nonlinear optical properties of 3-methyl-4- nitropyridine-1-oxyde (POM) crystal. The polarizability and first hyperpolarizability of increasingly large one-dimensional, two-dimensional and three-dimensional clusters of POM were evaluated. Time-dependent Hartree-Fock approach was used to determine the static and dynamic responses in combination with semiempirical Austin model 1 Hamiltonian. Second-order MØller- Plesset perturbation theory was used for assessment of the electron correlation effects for the POM monomer and dimer. Use of a sum-over-states method to attribute the first hyperpolarizability to a charge-transfer excited state was also described.