Formulae for the static electronic polarizability and hyperpolarizability are derived in terms of moments of the ground-state electron density matrix by applying the Unsöld approximation and a generalization of the Fermi-Amaldi approximation. The latter formula for the hyperpolarizability appears to be new. The formulae manifestly transform correctly under rotations, and they are observed to be essentially cumulant expressions. Consequently, they are additive over different regions. The properties of the formula are discussed in relation to others that have been proposed in order to clarify inconsistencies. The formulae are then tested against coupled-perturbed Hartree-Fock results for a set of 40 donor-π-acceptor systems. For the polarizability, the correlation is reasonable; therefore, electron density matrix moments from theory or experiment may be used to predict polarizabilities. By constrast, the results for the hyperpolarizabilities are poor, not even within one or two orders of magnitude. The formula for the two- and three-particle density matrices obtained as a side result in this work may be interesting for density functional theories. © 2018 CSIRO.

Parthapratim Munshi

Chemistry

(SoNS) School of Natural Sciences

Jayatilaka D.

Jha K.K.

<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

Is it Reasonable to Obtain Information on the Polarizability and Hyperpolarizability Only from the Electron Density

Australian Journal of Chemistry

A lightweight organic material, trans-4′-dimethylamino-4-nitro-α-cyanostilbene, exhibits notable charge carrier mobility (∼10 -4 cm 2 V -1 s -1 ). The non-centrosymmetric material also displays moderate second harmonic generation activity. This is one of the rarest examples of small organic materials displaying semiconductor characteristics. The charge-transfer pathway as elucidated via high-resolution single-crystal X-ray diffraction data based "energy frameworks" and "experimental charge density" analyses is assessed by measuring the charge carrier mobility using the space charge limited current technique on pure single-crystal diode devices. These advanced structural analyses clearly demonstrate that charge transport in organic crystals is purely governed by its molecular packing, especially the π-π stacking geometry. The balanced ambipolar charge transport behavior makes this highly soluble and thermally stable organic crystal promising for applications in optoelectronic devices. Moreover, this report introduces the crucial role of energy frameworks and charge density analyses for fundamental understanding of the structure-property relationship in organic semiconductors. Copyright © 2019 American Chemical Society.

Crystal Growth and Design

Structure-Property Relationship in an Organic Semiconductor: Insights from Energy Frameworks, Charge Density Analysis, and Diode Devices

The Journal of Chemical Physics

Modeling electron density distributions from X-ray diffraction to derive optical properties: Constrained wavefunction versus multipole refinement

Physics Reports

Sum rules and scaling in nonlinear optics

The Journal of Physical Chemistry C

Molecular Origins of the High-Performance Nonlinear Optical Susceptibility in a Phenolic Polyene Chromophore: Electron Density Distributions, Hydrogen Bonding, and ab Initio Calculations

Journal of Applied Physics

Identifying and evaluating organic nonlinear optical materials via molecular moments

The Journal of Physical Chemistry A

Theoretical Study of the Effect of Structural Modifications on the Hyperpolarizabilities of Indigo Derivatives

Is it Reasonable to Obtain Information on the Polarizability and Hyperpolarizability only from the Electron Density?