The recently introduced Local Coherent-State Approximation (LCSA) method (R. Martinazzo, M. Nest, P. Saalfrank and G.F. Tantardini, \emph{J. Chem. Phys.} \textbf{125}, 194102 (2006)) is a time-dependent, multiconfiguration method of the general G-MCTDH type which has been specifically tailored to deal with system-bath dynamical problems. In the usual system-bath picture, it uses discrete variable representation (DVR) states for the subsystem and Hartree products of coherent-states (CSs) for local bath states, in such a way to capture the important system-bath correlations and to scale linearly with respect to the number of bath degrees of freedom. Some generalizations of the method are introduced, ranging from locally multiconfigurational variants to generalized mixed quantum-classical schemes. In the multiconfiguration variants the Hartree approximation is relaxed while preserving the linear scaling property, and local bath states are described by superposition of CSs products. In the generalized mixed quantum-classical approaches, locality is reduced and each bath configuration is used for groups of subsystem DVR states. These extensions include a DVR-based, full G-MCTDH method and the traditional mixed quantum-classical approach as limiting cases. Applications to model system-bath problems at $T=0$ K (e.g. vibrational relaxation, tunneling and surface sticking) are discussed and results are compared with exact MCTDH ones in systems with $50-100$ bath degrees of freedom.

The Local Coherent-State Approximation to System-Bath quantum dynamics / R. Martinazzo. ((Intervento presentato al convegno The Quantum World in Real Time: Is It Accessible? tenutosi a Safed, Israel nel 2007.

### The Local Coherent-State Approximation to System-Bath quantum dynamics

#### Abstract

The recently introduced Local Coherent-State Approximation (LCSA) method (R. Martinazzo, M. Nest, P. Saalfrank and G.F. Tantardini, \emph{J. Chem. Phys.} \textbf{125}, 194102 (2006)) is a time-dependent, multiconfiguration method of the general G-MCTDH type which has been specifically tailored to deal with system-bath dynamical problems. In the usual system-bath picture, it uses discrete variable representation (DVR) states for the subsystem and Hartree products of coherent-states (CSs) for local bath states, in such a way to capture the important system-bath correlations and to scale linearly with respect to the number of bath degrees of freedom. Some generalizations of the method are introduced, ranging from locally multiconfigurational variants to generalized mixed quantum-classical schemes. In the multiconfiguration variants the Hartree approximation is relaxed while preserving the linear scaling property, and local bath states are described by superposition of CSs products. In the generalized mixed quantum-classical approaches, locality is reduced and each bath configuration is used for groups of subsystem DVR states. These extensions include a DVR-based, full G-MCTDH method and the traditional mixed quantum-classical approach as limiting cases. Applications to model system-bath problems at $T=0$ K (e.g. vibrational relaxation, tunneling and surface sticking) are discussed and results are compared with exact MCTDH ones in systems with $50-100$ bath degrees of freedom.
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http://www.weizmann.ac.il/conferences/qmdyn-2007/home.htm
The Local Coherent-State Approximation to System-Bath quantum dynamics / R. Martinazzo. ((Intervento presentato al convegno The Quantum World in Real Time: Is It Accessible? tenutosi a Safed, Israel nel 2007.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/185233
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