The fundamental ERI [912] and the basis of all ERI algorithms is usually represented

(B.3) |

which can be reduced to a one-dimensional integral of the form

(B.4) |

and can be efficiently computed using a modified Chebyshev interpolation scheme [914]. Equation (B.4) can also be adapted for the general case integrals required for most calculations. Following the fundamental ERI, building up to the full bra-ket ERI (or intermediary matrix elements, see later) are the problems of angular momentum and contraction.

**Note: **Square brackets denote primitive integrals and parentheses denote fully-contracted integrals.