Dynamic Mechanical Behaviour of Organic Molecular Crystals. II. Elastic Constants of Single-Crystal Anthracene

The thirteen elastic constants, Cij, and the elastic compliances, sij, of monoclinic single-crystal anthracene were determined from sound velocities measured by the ultrasonic pulse method at room temperture. The observed elastic constants were C11=8.92, C12=4.63, C13=4.49, C15=−2.58, C22=13.8, C23=8.45, C25=−2.59, C33=17.0, C35=−2.88, C44=2.42, C46=1.14, C55=2.84 and C66=−3.16 (in units of 1010 dyn/cm2). The hydrostatic linear compressibilities, β, of the anthracene molecular crystal were then calculated from these elastic constants and compliances; the β along [100] was 12.7×10−12 cm2/dyn, β[010]=4.41×10−12 cm2/dyn, and β[001]=3.59×10−12 cm2/dyn.