In theoretical developments, thermodynamic constraints are introduced by putting the system of interest in contact with some other virtually infinite system, the `reservoir', with a coupling vanishingly small in the thermodynamic limit. Neither ofthese `infinite' conditions can be reproduced in molecular dynamics simulations where the time evolution of an isolated system with a finite number of degrees of freedom is numerically integrated, producing trajectories representative of the microcanonical ensemble. Several ways have been proposed to overcome this limitation. Here the case of MD simulations at constant temperature and/or pressure will be treated within the extended system framework introduced by Andersen in his1980 seminal paper, and later generalised mainly by Nos\'e.The $N$-particle physical system of interest is put in contact with externalreservoirs, which are, in contrast to theoretical infinite ones, represented just bya few degrees of freedom. The equations of motion for the extended system are chosenin such a way that the dynamical trajectory in the phase space of the system ofinterest is representative of the desired ensemble. Moreover the coupling isnon-linear yielding good ergodic properties and can be chosen to be weak enough to leavethe dynamical properties of the system of interest unaltered.

THERMODYNAMIC CONSTRAINTS / Ferrario, Mauro. - STAMPA. - 397:(1993), pp. 153-171. (Intervento presentato al convegno NATO ADVANCED STUDY INST ON NEW PERSPECTIVES IN COMPUTER SIMULATION IN CHEMICAL PHYSICS tenutosi a ALGHERO, ITALY nel SEP 14-24, 1992).

THERMODYNAMIC CONSTRAINTS

FERRARIO, Mauro
1993

Abstract

In theoretical developments, thermodynamic constraints are introduced by putting the system of interest in contact with some other virtually infinite system, the `reservoir', with a coupling vanishingly small in the thermodynamic limit. Neither ofthese `infinite' conditions can be reproduced in molecular dynamics simulations where the time evolution of an isolated system with a finite number of degrees of freedom is numerically integrated, producing trajectories representative of the microcanonical ensemble. Several ways have been proposed to overcome this limitation. Here the case of MD simulations at constant temperature and/or pressure will be treated within the extended system framework introduced by Andersen in his1980 seminal paper, and later generalised mainly by Nos\'e.The $N$-particle physical system of interest is put in contact with externalreservoirs, which are, in contrast to theoretical infinite ones, represented just bya few degrees of freedom. The equations of motion for the extended system are chosenin such a way that the dynamical trajectory in the phase space of the system ofinterest is representative of the desired ensemble. Moreover the coupling isnon-linear yielding good ergodic properties and can be chosen to be weak enough to leavethe dynamical properties of the system of interest unaltered.
1993
NATO ADVANCED STUDY INST ON NEW PERSPECTIVES IN COMPUTER SIMULATION IN CHEMICAL PHYSICS
ALGHERO, ITALY
SEP 14-24, 1992
397
153
171
Ferrario, Mauro
THERMODYNAMIC CONSTRAINTS / Ferrario, Mauro. - STAMPA. - 397:(1993), pp. 153-171. (Intervento presentato al convegno NATO ADVANCED STUDY INST ON NEW PERSPECTIVES IN COMPUTER SIMULATION IN CHEMICAL PHYSICS tenutosi a ALGHERO, ITALY nel SEP 14-24, 1992).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/741406
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