Energy of a CI Wave Function

Finally some practical considerations. The time required for diagonalizing a matrix grows as the cube of the size of the matrix, and the amount of computer memory necessary for storing the matrix grows as the square of the size. Diagonalizing matrices up to 100 X 100 takes insignificant amounts of time, unless there are extraordinarily 

Many problems in computational chemistry can be formulated as an optimization of a multidimensional function. Optimization is a general term for finding stationary points of a function, i.e. points where tlie first derivative is zero. In the majority of cases the desired stationary point is a minimum, i.e. all the second derivatives should be positive. In some cases the desired point is a first-order saddle point, i.e. the second derivative is negative in one, and positive in all other, directions. Some 

The simple-minded approach for minimizing a function is to step one variable at a time until the fiinction has reached a minimum, and then switch to another variable. This 

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