Orbital symmetrisation of the recursion method

A new recursion algorithm which is free from symmetry difficulties in the resultant Green function associated with the axis rotation is developed as a straightforward matrix extension of the conventional recursion method of Haydock and co-workers (1975, 1980). The present method is particularly useful when one needs to calculate the symmetry preserving inter-site Green function from a relatively small number of the recursion coefficients, or whenever the symmetry properties of the Green function is important.