Quantum Monte Carlo estimation of complex-time correlations for the study of the ground-state dynamic structure function
We present a method based on the path integral Monte Carlo formalism for the calculation of ground-state time correlation functions in quantum systems. The key point of the method is the consideration of time as a complex variable whose phase δ acts as an adjustable parameter. By using high-order ap...
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Veröffentlicht in: | The Journal of chemical physics 2015-03, Vol.142 (11), p.114114-114114 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We present a method based on the path integral Monte Carlo formalism for the calculation of ground-state time correlation functions in quantum systems. The key point of the method is the consideration of time as a complex variable whose phase δ acts as an adjustable parameter. By using high-order approximations for the quantum propagator, it is possible to obtain Monte Carlo data all the way from purely imaginary time to δ values near the limit of real time. As a consequence, it is possible to infer accurately the spectral functions using simple inversion algorithms. We test this approach in the calculation of the dynamic structure function S(q, ω) of two one-dimensional model systems, harmonic and quartic oscillators, for which S(q, ω) can be exactly calculated. We notice a clear improvement in the calculation of the dynamic response with respect to the common approach based on the inverse Laplace transform of the imaginary-time correlation function. |
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ISSN: | 0021-9606 1089-7690 |
DOI: | 10.1063/1.4914995 |