Calculation of birefringence changes in anthracene and phenanthrene crystals

P. J. Bounds, R. W. Munn

    Research output: Contribution to journalArticlepeer-review


    Birefringence changes due to thermal expansion were calculated for anthracene and phenanthrene. The method assumes that the effective molecular polarizability calculated at room temperature is constant in the molecular axis system for small changes of molecular orientation and separation. For anthracene, the calculations reproduce the observed birefringence change quantitatively. For phenanthrene, two thirds of the observed change is due to thermal expansion, the rest to structural alterations at the 70 degree C phase transition; transition to a Pa structure is ruled out. Birefringence calculations could be used to test other high-temperature structures for phenanthrene which might be suggested by lattice-energy calculations.

    Original languageEnglish
    Pages (from-to)301-308
    Number of pages8
    JournalMolecular Crystals and Liquid Crystals
    Issue number3-4
    Publication statusPublished - 1978


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