DOUBLE-WELL POTENTIAL - THE WKB APPROXIMATION WITH PHASE LOSS AND ANHARMONICITY EFFECT

We derive a general WKB energy splitting formula in a double-well pote ntial by incorporating both phase loss and the anharmonicity effect in the usual WKB approximation. A bare application of the phase loss app roach to the usual WKB method gives better results only for large sepa ration between two potential minima. In the range of substantial tunne ling, however, the phase loss approach with the anharmonicity effect c onsidered leads to a great improvement in the accuracy of the WKB appr oximation. [S1050-2947(98)01411-5].