Electrostatic potentials and Mulliken net atomic charges were calculated from STO-3G, 6-31G, and 6-31G* * SCF-MO wavefunctions for hydrogen fluoride, water, ammonia, methane, acetylene, ethylene, carbon dioxide, formaldehyde, methanol, formamide, formic acid, acetonitrile, diborane, and carbonate ion. In each case optimized net atomic charges (potential-derived charges) were also obtained by fitting the electrostatic potentials calculated directly from the wavefunctions in a shell enveloping the molecules outside of their van der Waals surfaces. The electrostatic potentials calculated from the potential-derived charge distributions were then compared with the defined quantum mechanical electrostatic potentials and with the electrostatic potentials of the Mulliken charge distributions.

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Inclusion of polar organic molecules in molecular sieve hosts has been investigated as a means of creating self-assembled aggregates of molecules that possess the noncentrosymmetry required for materials to exhibit second harmonic generation (SHG). Aluminophosphate molecular sieves with one-dimensional channel structures are shown by SHG powder measurements to successfully direct this self-aggregation for a number of organic molecules including and related to p-nitroaniline. Models supported by FTIR evidence show the aggregates could be chains of molecules with a large net dipole that form within the molecular sieve channels. The polar host crystal then aligns the aggregates to produce a large bulk dipole moment and the observed SHG signal. Three methods for controlling the SHG intensity within a particular host structure have been elucidated: (1) variation of guest concentration, (2) alteration of guest structure, and (3) changing the charge density on the host framework.