Angular variation of electron paramagnetic resonance spectrum: Simulation of a polycrystalline EPR spectrum

A procedure based on homotopy, involving a quick calculation of EPR line po sitions for various orientations of the external magnetic field by the meth od of least-squares fitting and Taylor-series expansion, using a known line position at an infinitesimally close orientation of the external magnetic field as the initial value, by using the eigenvectors and eigenvalues of th e spin-Hamiltonian matrix in single crystals, has been exploited to simulat e a polycrystalline EPR spectrum. This requires rigorous calculations of in tensities of resonant lines, along with their positions. Specifically, deta ils are given of the numerical techniques involving time-efficient matrix d iagonalization to obtain the eigenvalues and eigenvectors required to calcu late positions and intensities of EPR lines by the method of least-squares fitting. Finally, the procedure of how to simulate a polycrystalline EPR sp ectrum is outlined, the required steps are listed, and illustrative example s are given. (C) 1999 Academic Press.