Interrelationship «Composition - Structure - Property» for Acentric Selenite Crystals

For the first time the structure, chemical bond lengths and nonlinear optical (NLO) susceptibility are tabulated for more than 100 noncentresymmetric (NCS) crystals of the simple and binary selenites. It is shown that in the plane of the metal-oxide bond lengths these crystals are positioned inside of the horizontal and slope intersected ellipses of "acentricity". The crystals with high NLO susceptibility are found near the right border of the vertical ellipse, and near the upper border of the horizontal ellipse; with the moderate one - into the left and central parts of these ellipses, and with low susceptibility into the top and bottom of ellipses rosette. The un-monotonous, extreme, fuzzy dependency of the NLO -susceptibility on the oxide bond length is observed.