Analytical second derivatives of two electron integrals oversandpCartesian Gaussians

摘要

An efficient algorithm for computing second derivatives of two electron integrals is outlined and has been coded forshyphen; andphyphen;type Cartesian Gaussians. This method is an extension of a previous algorithm for two electron integral first derivatives lsqb;H. B. Schlegel, J. Chem. Phys.77, 3676 (1982)rsqb; and is suitable for scalar machines with modest memories. Timing data indicates that the present algorithm is 3ndash;6 times faster than a scalar version of the Rys polynomial method. Furthermore, the computational time for the two electron integral second derivatives is only 2ndash;3 times longer than for the integral first derivatives by the same approach. The code has been incorporated in the recently released version ofgaussian88.