A Feynman path centroid dynamics approach for the computation of time correlation functions involving nonlinear operators

The centroid dynamics formalism is extended to the calculation of time correlation functions of nonlinear operators. It is shown that centroid correlation functions can be related to quantum mechanical ones via higher order Kubo-type transforms. A key step is the construction of the correlation functions from a mixed classical/semiclassical centroid representation of the operators. A general methodology is developed to relate these Kubo-type transforms to the desired quantum correlation functions. The approach is tested using a one-dimensional anharmonic potential for which the [x(2)x(2)(t)] and the [x(3)x(3)(t)] correlation functions are computed. Applications of this new approach are also outlined. (C) 2000 American Institute of Physics. [S0021-9606(00)50827-7].