CALCULATION OF PLANEWISE DIPOLE SUMS FOR ANTHRACENE CRYSTAL

Planewise dipole sums are calculated for various lattice planes in anthracene, treated both as a single point and as three point submolecules. Conventional methods, generalized to treat submolecules, are used as well as a new method using partial reverse Fourier transformation of modulated bulk lattice dipole sums. The new method gives an independent check but is not otherwise preferable. The submolecule treatment makes the interaction between adjacent planes not much less than within a plane, essentially because of the molecular packing. Beyond adjacent planes, the sums decrease exponentially by typically a factor of 100 per 10 angstrom separation. Calculations for arbitrary planes are conveniently performed by transforming the conventional crystal unit cell to contain the desired plane as a face. Wave vector-modulated planewise sums have also been calculated for point molecules and the (001) plane: They decrease less rapidly with separation than unmodulated sums.