Efeito do ambiente cristalino sobre as propriedades elétricas da L-arginina fosfatada monohidratada: uma abordagem teórica via teoria do funcional da densidade

Abstract

The appearance of the Optoelectronics together with the discovery in the decade of 60 of a new area of research named Molecular Modeling, stimulated the development of new materials whose properties provide its employment in the context of the Optoelectronics . The L-arginine phosphate monohydrate (LAP) is an organic-inorganic crystal highly transparent with attractive properties for conversion of frequency and among its properties, non-linear devices can be easily made from them. Along this work it was used a supermolecule approach and an iterative electrostatic polarization scheme to get properties of asymmetric unit of L-arginine phosphate monohydrate (LAP), they are: the moment of the dipole (μ), linear polarizability (α), first hyperpolarizability (β), second hyperpolarizability (γ) and molecular orbital border (HOMO and LUMO), both for the isolated molecule, as embedded in the polarization field of the surrounding molecules treated as point charges. The moment of the dipole was determined through MP2 and DFT calculations using the set of basic functions 6−311+G(d). We tested the functional density B3LY P, B2PLY P, WB97, M06HF and CAM − B3LY P, and it was observed that B2PLY P and B3LY P provided better results when compared to those obtained in level MP2 and the experimental data. The moment of the dipole calculated in the DFT with the functional level B3LY P showed the best results related to its experimental value, differing by only 3%. The other electric properties were calculated only at level DFT. Both for the linear polarizability (α), in which the results for functional CAM − B3LY P differs in 0, 93%, as for the first hyperpolarizability (β), whose values for WB97 do not present percentage difference, note that the results are satisfactory when compared to those obtained in the level of theory MP2. For the calculation of the second hyperpolarizability (γ) was not feasible the comparison with another level of theory and experimental data, once there is no work regarding this LAP property in the literature. Also considering the functional CAM −B3LY P, when compared isolated molecule and involved it was observed an increase of 5% in Band-Gap through the calculation of HOMO and LUMO orbitals.