Papadopoulos, M. G. (1999). Molecular simulation of static hyper-Rayleigh scattering : a calculation of the depolarization ratio and the local fields for liquid nitrobenzene. Journal of Chemical Physics, 111(21), 9711-9719. DOI: 10.1063/1.480305 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Molecular dynamics ͑MD͒ simulation is used to assess the hyper-Rayleigh scattering ͑HRS͒ depolarization ratio of liquid nitrobenzene subject to vertically polarized light. In contrast to previous theoretical work, we have quantified both incoherent and coherent scattering arising from positional and orientational inhomogeneities in the molecular distribution. Although coherent scattering is shown to be much less important than in the case of Rayleigh scattering, it can not be neglected. Therefore, our analysis supports the current practice of working with dilute solutions ͑for which coherent contributions to HRS are truly negligible͒ to extract the first molecular hyperpolarizability from HRS measurements. In cases where experiments with pure liquids can not be circumvented, our analysis may be used to separate coherent and incoherent signals. Our work, which uses as input static ''gas-phase'' ͑hyper͒polarizabilities obtained from ab initio calculations, also provides information on the orientations and magnitudes of the local electric fields experienced by the individual molecules in the liquid. For nitrobenzene it is found that the local fields are largely determined by specific dipolar alignment between neighboring pairs of molecules, with consequences on the HRS signal.

. Computer simulation of the linear and nonlinear optical properties of liquid benzene : its local fields, refractive index and second nonlinear susceptibility. Journal of Chemical Physics, 110(13), 6463-6474. DOI: 10.1063/1.478549 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Molecular dynamics ͑MD͒ simulation and subsequent analysis of the macroscopic polarization developed in response to ''a posteriori'' applied electric fields or of spontaneous fluctuations in the instantaneous polarization under zero applied field is used to assess the nonlinear optical properties of a polarizable liquid. Three strategies are proposed for the electrostatic analysis, all using as input static ''gas phase'' ͑hyper͒polarizabilities, obtained from ab initio calculations. All three strategies are shown to accurately reproduce the experimentally measured refractive index and second nonlinear susceptibility of liquid benzene. The simulation also predicts the distribution of orientations and magnitudes of the local electric fields experienced by the molecules in the liquid, and the nonlinear contributions to the local fields. This approach gives an 8% higher estimate of the second nonlinear susceptibility of liquid benzene than the Lorentz local field factor approach, in better agreement with experimental values.