منابع مشابه
Variational Perturbation Theory for Density Matrices
Variational perturbation theory [1,2] transforms divergent perturbation expansions into convergent ones. The convergence extends to infinitely strong couplings [3], a property which has recently been used to derive critical exponents in field theory without renormalization group methods [4,5]. The theory has first been developed in quantum mechanics for the path integral representation of the f...
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We present a method for evaluating divergent series with factorially growing coefficients of equal sign. The method is based on an analytic continuation of variational perturbation theory from the regime of alternating signs. We demonstrate its power first by applying it to the exactly known partition function of the anharmonic oscillator in zero space–time dimensions (the simple integral). The...
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Variational perturbation theory was used to solve the Schrödinger equation for a hydrogen atom confined at the center of an impenetrable cavity. Ground state and excited state energies and expectation values calculated from the perturbation wavefunction are comparable in accuracy to results from direct numerical solution.
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The perturbation theory for critical points of causal variational principles is developed. We first analyze the class of perturbations obtained by multiplying the universal measure by a weight function and taking the push-forward under a diffeomorphism. Then the constructions are extended to convex combinations of such measures, leading to perturbation expansions for the mean and the fluctuatio...
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We present a Rayleigh-Schrödinger-Goldstone perturbation formalism for many fermion systems. Based on this formalism, variational perturbation scheme which goes beyond the Gaussian approximation is developed. In order to go beyond the Gaussian approximation, we identify a parent Hamiltonian which has an effective Gaussian vacuum as a variational solution and carry out further perturbation with ...
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ژورنال
عنوان ژورنال: International Journal of Modern Physics A
سال: 1994
ISSN: 0217-751X,1793-656X
DOI: 10.1142/s0217751x94000832