Accession Number : ADA306197

Title :   Non-Linear Optical Effects in Molecules.

Descriptive Note : Final rept. 1 Feb 93-31 Jan 96,

Corporate Author : FLORIDA UNIV GAINESVILLE

Personal Author(s) : Bartlett, Rodney J.

PDF Url : ADA306197

Report Date : 31 MAR 1996

Pagination or Media Count : 42

Abstract : We analyze the evolution of first principle molecular theory in obtaining reliable values of molecular hyperpolarizabilities. Such quantities place severe demands on the capability of quantum chemistry, as large basis sets, frequency dependence, and high levels of electron correlation are all shown to be essential in obtaining observed, gas phase hyperpolarizabilities to within an error of 10%. Ab initio Hartree Fock results are typically in error by nearly a factor of two, while the errors due to the neglect of frequency dependence average about 1O to 3O% depending upon the particular process. It is also shown that for small molecules, standard semiempirical approaches, like INDO and INDO/S, will often not even give the correct sign for hyperpolarizabilities. It is demonstrated that using state of the art correlated, frequency dependent methods, it is possible to provide results to within 10%. Excluding any one of the essential elements, though, destroys the agreement

Descriptors :   *OPTICAL PROPERTIES, *MOLECULAR STRUCTURE, POLARIZATION, QUANTUM CHEMISTRY, STATE OF THE ART, MOLECULES, THEORY, VAPOR PHASES, CORRELATION, NONLINEAR SYSTEMS.

Subject Categories : Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE