## Abstract

Theoretical computational methods relevant to low-energy electron scattering rely on variational principles. Variational theory appropriate to representation of the (*N +* 1)-electron scattering wave function in the form of Eq. (1.1) will be presented in this chapter. Direct computational application of this formalism is referred to here as the *matrix variational method*. Since it has been shown in Chapter 1 how the widely applied close-coupling method can be described by Eq. (1.1), the general variational argument to be given here also applies to that method, with some modifications of detail. In the *algebraic close-coupling method* this variational formalism, rather than numerical integration, is used to obtain solutions of the coupled equations as linear combinations of basis functions.

## Keywords

Variational Principle Variational Theory Closed Channel Fixed Boundary Condition Channel Orbital## Preview

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