/** * \file IMP/atom/BerendsenThermostatOptimizerState.h * \brief Maintains temperature during molecular dynamics using a * Berendsen thermostat. * * Copyright 2007-2013 IMP Inventors. All rights reserved. * */ #ifndef IMPATOM_BERENDSEN_THERMOSTAT_OPTIMIZER_STATE_H #define IMPATOM_BERENDSEN_THERMOSTAT_OPTIMIZER_STATE_H #include #include #include #include #include IMPATOM_BEGIN_NAMESPACE //! Maintains temperature during molecular dynamics. /** The thermostat scales velocities using the algorithm described in H. J. C. Berendsen, J. P. M. Postma, W. F. van Gunsteren, A. DiNola, and J. R. Haak "Molecular dynamics with coupling to an external bath", Journal of Chemical Physics 81 pp. 3684-3690 (1984). At each update, velocities are rescaled by \f[ \lambda = \left[1 + \frac{\Delta t}{\tau_T} \left( \frac{T}{T_k} -1\right)\right]^{1/2} \f] where \f$\Delta t\f$ is the molecular dynamics timestep, \f$\tau_T\f$ is the coupling constant (in fs) of the thermostat, \f$T\f$ is the thermostat temperature, and \f$T_k\f$ is the instantaneous (kinetic) temperature of the dynamics. (This is equation 11 from the reference above.) */ class IMPATOMEXPORT BerendsenThermostatOptimizerState : public OptimizerState { public: BerendsenThermostatOptimizerState(const Particles &pis, double temperature, double tau); //! Set the particles to use. void set_particles(const Particles &pis) { pis_=pis; } double get_temperature() { return temperature_; } double get_tau() { return tau_; } void set_temperature(double temperature) { temperature_ = temperature; } void set_tau(double tau) { tau_ = tau; } //! Rescale the velocities now void rescale_velocities() const; IMP_OPTIMIZER_STATE(BerendsenThermostatOptimizerState); private: Particles pis_; double temperature_; double tau_; //! Keys of the xyz velocities FloatKey vs_[3]; }; IMP_OBJECTS(BerendsenThermostatOptimizerState, BerendsenThermostatOptimizerStates); IMPATOM_END_NAMESPACE #endif /* IMPATOM_BERENDSEN_THERMOSTAT_OPTIMIZER_STATE_H */