CRAFT database for development and testing force fields

Leonid Pereyaslavets, Alexei Finkelstein
2010 Acta Crystallographica Section A Foundations of Crystallography  
The calculation of the nonlinear optical (NLO) properties of solids using structural data has been stimulated by the increasing importance of the communications industry and the parallel need for materials having suitable properties. Classical molecular requirements for second-order NLO effects are strongly elongated and conjugated molecules, asymmetrized by interacting donor and acceptor groups. Although they often exhibit extremely large hyperpolarizabilities, some major drawbacks are
more » ... ed with their dipolar character, e.g. a high tendency towards unfavourable aggregation and small off-diagonal tensor components. It was recognized that octupolar molecules can circumvent the aforementioned disadvantages, since these nonpolar molecules combine excellent (second-order) NLO characteristics with a strict cancellation of all vectorial properties [1]. Several salts have been prepared by acid-base reactions of triphenylguanidine with 1,2,4,5-benzenetetracarboxylic, cyanoacetic, diphenylacetic and trithiocyanuric acids, and their single-crystal X-ray structure analysis has been performed. Using the methodology that we have developed recently [2], we calculated the nonlinear susceptibility tensor components for the non-centrosymmetric salts. An Hirshfeld surface analysis [3] has been performed to study the effect of the various crystalline environments on the triphenylguanidinium cation, namely the effect of the hydrogen bonding motifs.
doi:10.1107/s0108767310094171 fatcat:najw6hdomzerleoyve5v7v4cd4