Computer Synthesis of Electron Paramagnetic Resonance Spectra from a Parametric (Spin) Hamiltonian
A computer program has been developed for computing electron paramagnetic resonance (EPR) spectra from a spin Hamiltonian, ℋsp which is a linear combination of spin operators whose coefficients may be regarded as experimental parameters. The user supplies ℋsp, the spin number (orientation degeneracy) of each particle, and values of the parameters; output may be obtained in the form of the frequency spectrum for fixed applied magnetic-field strength, H0, or the magnetic-field spectrum for fixed radiation frequency, vmr. In addition to the line positions, the program computes first-order transition intensities in a radiation field H1 using eigenvectors generated by the calculation. Results have been obtained for (transition-metal) ions and free radicals in single crystals as a function of field orientation, and in powders and glasses (by summing over many orientations). The program can be adapted for calculation of NMR and NQR spectra of anisotropic systems, inclusion of line narrowing and broadening (relaxation) effects, and automatic adjustment of certain parameters to fit experimental spectra.
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