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A New u function


In a parallel development described in chapter gif a new method for evaluating the expectation value of the Coulomb interaction was introduced which relies on the short range of the exchange-correlation hole [3]. This method allows accurate results to be obtained without summing the interactions over periodic images of the simulation cell, thereby reducing the computational cost significantly and leaving the evaluation of the Jastrow factor as the most time consuming part of the calculation. Therefore, it was decided to seek a new form for u which is as accurate as the previous form in Eq.(gif), yet convenient for optimisation purposes and can be evaluated rapidly within a QMC calculation.

Andrew Williamson
Tue Nov 19 17:11:34 GMT 1996