Structural and dipole (hyper)polarizabilities of the ground and excited singlet states of urea and thiourea: A gas phase CIS(D) theoretical study

Issue title: II Congress of Theoretical and Computational Physical Chemistry, Choroni, Venezuela, 2008

Guest editors: H. Soscunxy, F. Ruettez and A. Sierraltaz

Article type: Research Article

Authors: Toro, Carlos^a | Hinchliffe, Alan^b | Arrieta, Federico^a | Urdaneta, Johan^a | Bermudez, Yaneth^a | Castellano, Olga^c | Soscún, Humberto^{a; d; *}

Affiliations: [a] Laboratorio de Química Inorgánica Teórica, Departamento de Quimica, Facultad Experimental de Ciencias, La Universidad del Zulia, Modulo II, Grano de Oro, Ap. 526, Maracaibo, Venezuela | [b] School of Chemistry, University of Manchester, Sackville Street, Manchester M60 1QD, UK | [c] PDVSA, Intevep. Los Teques, Edo. Miranda, Venezuela | [d] Centro Nacional de Tecnología Química, Complejo Tecnológico Simon Rodríguez, Base Aerea Generalísimo Francisco de Miranda, La Carlota, Caracas, Venezuela | [x] Centro Nacional de Tecnologia Quimica CNTQ, Complejo Tecnologico Simon Rodriguez CTSR, La Carlota, Caracas, Venezuela | [y] Departamento de Quimica, Facultad Experimental de Ciencias, La Universidad del Zulia LUZ, Maracaibo, Venezuela | [z] Centro de Quimica, Instituto Venezolano de Investigaciones Cientificas IVIC, Caracas, Venezuela

Correspondence: [*] Corresponding author. Tel.: +58 212 5550957; E-mail: [email protected].

Abstract: A study of the ground and the first five electronic excited singlet states properties of urea and thiourea molecules is reported. Our interest lies on structural features (bond distances and angles), electronic behavior (energy, dipole moment, charges), and the linear (polarizability) and nonlinear (first hyperpolarizability) optical properties of these relevant molecules within each excited state and how different they are from the ground state. Ground state properties were evaluated using ab initio and Density Functional Theory methods at HF, MP2, BLYP, and B3LYP levels on the corresponding optimized geometries, while excited states properties were determined through the CIS and CIS(D) procedures. The standard 6-31+G(d,p) and 6-311++G(3d,3p) basis sets were employed for all these calculations. The results of the ground state properties of urea and thiourea excellently agree with most of the available data in the literature. Moreover, excited state properties appear to be strongly affected within each state, and in general, they are quite different from the ground state values. Particularly, the first hyperpolarizability β represents the most affected property, and some interesting trends are proposed and discussed. Finally, based on our results, we suggest that a study of the excited state properties of both urea and thiourea derivatives can be useful as a guide for designing new nonlinear optical materials.

DOI: 10.3233/JCM-2009-0304

Journal: Journal of Computational Methods in Sciences and Engineering, vol. 9, no. 4-6, pp. 289-300, 2009