Your browser doesn't support javascript.
loading
Nonlocal stochastic-partial-differential-equation limits of spatially correlated noise-driven spin systems derived to sample a canonical distribution.
Gao, Yuan; Marzuola, Jeremy L; Mattingly, Jonathan C; Newhall, Katherine A.
Afiliación
  • Gao Y; Department of Mathematics, University of North Carolina at Chapel Hill, CB 3250, Chapel Hill, North Carolina 27599-3250, USA.
  • Marzuola JL; Department of Mathematics, University of North Carolina at Chapel Hill, CB 3250, Chapel Hill, North Carolina 27599-3250, USA.
  • Mattingly JC; Department of Mathematics and Department of Statistical Sciences, Duke University, Box 90320, Durham, North Carolina 27708-0320, USA.
  • Newhall KA; Department of Mathematics, University of North Carolina at Chapel Hill, CB 3250, Chapel Hill, North Carolina 27599-3250, USA.
Phys Rev E ; 102(5-1): 052112, 2020 Nov.
Article en En | MEDLINE | ID: mdl-33327182
For a noisy spin system, we derive a nonlocal stochastic version of the overdamped Landau-Lipshitz equation designed to respect the underlying Hamiltonian structure and sample the canonical or Gibbs distribution while being driven by spatially correlated (colored) noise that regularizes the dynamics, making this Stochastic partial differential equation mathematically well-posed. We begin from a microscopic discrete-time model motivated by the Metropolis-Hastings algorithm for a finite number of spins with periodic boundary conditions whose values are distributed on the unit sphere. We thus propose a future state of the system by adding to each spin colored noise projected onto the sphere, and then accept this proposed state with probability given by the ratio of the canonical distribution at the proposed and current states. For uncorrelated (white) noise this process is guaranteed to sample the canonical distribution. We demonstrate that for colored noise, the method used to project the noise onto the sphere and conserve the magnitude of the spins impacts the equilibrium distribution of the system, as coloring projected noise is not equivalent to projecting colored noise. In a specific scenario we show this break in symmetry vanishes with vanishing proposal size; the resulting continuous-time system of Stochastic differential equations samples the canonical distribution and preserves the magnitude of the spins while being driven by colored noise. Taking the continuum limit of infinitely many spins we arrive at the aforementioned version of the overdamped Landau-Lipshitz equation. Numerical simulations are included to verify convergence properties and demonstrate the dynamics.

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Phys Rev E Año: 2020 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Estados Unidos

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Phys Rev E Año: 2020 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Estados Unidos