Application of the discrete Wentzel–Kramers–Brillouin method to spin tunneling

A discrete version of the Wentzel–Kramers–Brillouin (WKB) method is developed and applied to calculate the tunnel splittings between classically degenerate states of spin Hamiltonians. The results for particular model problems are in complete accord with those previously found using instanton methods. The discrete WKB method is more elementary and also yields wave functions.

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