Basis set and electron correlation effects on ab initio electronic and vibrational nonlinear optical properties of conjugated organic molecules

Torrent-Sucarrat, Miquel; Solà, Miquel; Duran, Miquel; Luis, Josep M.; Kirtman, Bernard

doi:doi:10.1063/1.1521725

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Density inhomogeneities and electron mobility in supercritical xenon

The low-field mobility of electrons in supercritical Xe has been measured isothermally as a function of density above the critical temperature (289.7 K). At 293 K the mobility varies from a high of 890 cm2/V s at 9.2×1021 atoms/cm3 to a minimum value of 4.6 cm2/V s at a density of 3.5×1021 atoms/cm3, which is just below the critical density. The density dependence of the mobility is reasonably well predicted by the deformation potential model if the adiabatic compressibility is used to characte...

Relaxation of the structure of simple metal ion complexes in aqueous solutions at up to supercritical conditions

Our previous x-ray absorption fine structure studies of aqueous solutions revealed relaxation of the structure of complexes of Zn2+, Fe2+, La3+, and Yb3+ ions with increasing temperature. These complexes in general exhibit reduction of cation–ligand bond lengths with increasing temperature due to hydrogen bond breaking and loss of water of solvation. Because this results in an overall lowering of the equilibrium state of the complex, we refer to the variation of the structure as relaxation. In t...

We have studied how the calculation of electronic and vibrational contributions to nonlinear optical properties of three representative π-conjugated organic molecules is affected by the choice of basis set and the inclusion of electron correlation effects. The 6-31G basis does not always provide even qualitative accuracy. For semiquantitative accuracy a 6-31+G(d) basis is sufficient. Although, as compared to QCISD, a second-order Møller–Plesset (MP2) treatment often yields a substantial fraction of the electron correlation contribution, our MP2 results for the separate electronic and vibrational terms are not consistently of semiquantitative accuracy. Nevertheless, at the MP2 level the ratio between the vibrational and electronic contributions is satisfactorily reproduced. © 2003 American Institute of Physics.