A DENSITY FUNCTIONAL THEORY OF POLYATOMIC FREEZING

Functional expansion techniques are used to develop a polyatomic theory of freezing. In the appropriate limit, the resulting theory reduces to the Ramakrishnan-Yussouff-Haymet-Oxtoby theory of freezing for monatomic systems. The interaction site formalism is used to describe the molecules and, as a bonus, a new closure for the RISM liquid state theory is proposed. The freezing theory is used to investigate the plastic crystal phase for hard dumbells. Solid-like solutions are found for bond lengths smaller than 0.19(sigma), where (sigma) is the diameter of each sphere in the dumbell. The equations are solved by both a Gaussian like approximation and by a full solution in Fourier space