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Quantum Monte Carlo estimation of complex-time correlations for the study of the ground-state dynamic structure function
Rota, R; Casulleras Ambrós, Joaquín; Mazzanti Castrillejo, Fernando Pablo; Boronat Medico, Jordi
Universitat Politècnica de Catalunya. Departament de Física i Enginyeria Nuclear; Universitat Politècnica de Catalunya. SIMCON - Grup de Recerca de Simulació per Ordinador en Matèria Condensada
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 d 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 d 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, omega) of two one-dimensional model systems, harmonic and quartic oscillators, for which S(q, omega) 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. (C) 2015 AIP Publishing LLC.
Àrees temàtiques de la UPC::Física
Monte Carlo method
Quantum systems
Path integrals
Analytic continuation
Analytic continuation
Path-integrals
Maximum-entropy
Rate constants
Systems
Simulations
Monte Carlo, Mètode de
Quàntums, Teoria dels
Integrals
Attribution-NonCommercial-NoDerivs 3.0 Spain
http://creativecommons.org/licenses/by-nc-nd/3.0/es/
info:eu-repo/semantics/submittedVersion
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