# Rotation of real spherical harmonics

## Description

Abstract In many physical problems, such as the calculation of interactions between multipoles, the rotation of spherical harmonics is necessary. In this paper, a computer program for the rotation of real spherical harmonics is reported. The program is designed for calculating sets of rotation matrices, for given Eulerian angles, and exploits some recurrence relations which make possible an important reduction of computational cost. Title of program: ROTAR Catalogue Id: ABHI_v1_0 Nature of problem Given a certain coordinate system and the Eulerian angles, the program provides the rotation matrices needed for transforming real normalized spherical harmonics defined in the first system to those of the second one. CORRECTION SUMMARY: Vol:Year:Page 62:1991:162 "000A CORRECTION 02/05/90" "Rotation of real spherical harmonics. (C.P.C. 52(1989)323)." J.R. Alvarez Collado; J. Fernandez Rico; R. Lopez; M. Paniagua; G. Ramirez Note: correction instructions are contained in source code Versions of this program held in the CPC repository in Mendeley Data ABHI_v1_0; ROTAR; 10.1016/0010-4655(89)90107-0 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)