A NEW GEOMETRICALLY BASED INTEGRAL-EQUATION HIERARCHY FOR HARD-SPHERESYSTEMS .2. PAIR AND TRIPLET BACKGROUND CORRELATION-FUNCTIONS

A new exact hierarchy of integral equations is used for the background correlation functions of hard-sphere systems (Labik, S., Malijevsky, A. and Smith, W. R., 1994, Molec. Phys., 83, 983) to calculate the pai r and triplet background correlation functions. Also, a new computer s imulation method is introduced to calculate the derivative of the back ground pair correlation function with respect to distance, and use it to calculate this derivative at the contact distance. These results ar e compared with those of computer simulations and other theories, and it is found that the results using the second-order closure with the h ierarchy are generally quite accurate, and are better than those of al l other theories except the PY3 theory.