step.h

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/*
 * Copyright (C) 2007 by David J. Hardy.  All rights reserved.
 */

#ifndef STEP_H
#define STEP_H

#include "mdapi/mdtypes.h"

#ifdef __cplusplus
extern "C" {
#endif


  enum {
    STEP_FAILURE = -1,
    STEP_SUCCESS = 0
  };


  typedef enum StepMethod_t {
    STEP_VERLET = 1,
    STEP_SHADOW,
    STEP_TEMPBATH,
    STEP_NHEXP,
    STEP_DRUDE_NH,
    STEP_DRUDE_ROUX,
    STEP_DRUDE_CHEN,
    STEP_CGMIN,
    STEP_METHOD_MARKER

  } StepMethod;


  typedef enum StepOption_t {
    STEP_INITVEL   = 0x001,
    STEP_RESTARTVEL= 0x002,
    STEP_REMOVECOM = 0x004,
    STEP_ZEROLINMO = 0x008,
    STEP_SETTLE    = 0x010,
    STEP_VIRIAL    = 0x020,
    STEP_MOMENTUM  = 0x040,
    STEP_FIXEDATOMS= 0x080,
    STEP_CONSTRAINTS=0x100,
    STEP_OPTION_MARKER = 0x1FF

  } StepOption;


  struct StepSystem_t;
  typedef struct StepSystem_t StepSystem;


  typedef struct StepParam_t {

    StepMethod method;
    StepOption options;
    unsigned long random_seed;
    double timestep;
    double initial_temperature;
/*** callbacks ***/

    void *messageObjPtr;
    int (*output_message)(void *messageObjPtr, const char *msg);
    void *forceObjPtr;
    int (*compute_force)(void *forceObjPtr,
        double *pe, MD_Dvec *force, const MD_Dvec *pos);
    void *resultsObjPtr;
    int (*submit_results)(void *resultsObjPtr, StepSystem *sys);
    int32 resultsFreq;
    int32 init_stepnum;
/*** topology ***/

    MD_Atom *atom;
    int32 natoms;
#if 0
    MD_Bond *bond;
    int32 nbonds;
    MD_Angle *angle;
    int32 nangles;
/*** force field ***/

    MD_BondPrm *bondprm;
    int32 nbondprms;
    MD_AnglePrm *angleprm;
    int32 nangleprms;
#endif

/*** parameters for STEP_TEMPBATH ***/

    double bath_temperature;
    double relaxation_time;
/*** parameters for STEP_NHEXP ****/

    double nh_temperature;
    double nh_timescale;
/*** parameters for STEP_DRUDE ***/

    double drude_com_temperature;
    double drude_bond_temperature;
    double drude_com_timescale;
    double drude_bond_timescale;
    int32 drude_multisteps;
/*** parameters for STEP_CGMIN ***/

    double cgmin_dis;
    double cgmin_tol;
    int32 cgmin_eval;
/*** parameters for STEP_SETTLE option ***/

    double settle_oh_dist;
    double settle_hoh_angle;
  } StepParam;


  enum StepShadowIndex_t {
    STEP_SHADOW_4 = 0,    
    STEP_SHADOW_8,        
    STEP_SHADOW_12,       
    STEP_SHADOW_16,       
    STEP_SHADOW_20,       
    STEP_SHADOW_24,       
    STEP_SHADOW_MAXINDEX
  };


  struct StepSystem_t {

    double kinetic_energy;
    double temperature;
    MD_Dvec linear_momentum;
    MD_Dvec angular_momentum;
    double kinetic_virial[9];
    double potential_energy;
    double shadow_energy[STEP_SHADOW_MAXINDEX];
    double nh_extended_energy;
    double nh_friction_coef;
    double nh_log_s;
    double drude_com_energy;
    double drude_bond_energy;
    double drude_extended_energy;
    double drude_com_temperature;
    double drude_bond_temperature;
    MD_Dvec *force;
    MD_Dvec *vel;
    MD_Dvec *pos;
    int32 stepnum;
    int32 ndegfreedom;
    int32 nfixedatoms;
    int32 nrigidwaters;
  };


  struct Step_t;
  typedef struct Step_t Step;


  Step *new_Step(void);

  void delete_Step(Step *);

  int step_setup(Step *, StepParam *param,
      MD_Dvec *pos, MD_Dvec *vel, MD_Dvec *force);


  int step_compute(Step *, int32 numsteps);


  const char *step_errmsg(Step *);


  void step_cleanup(Step *);


#ifdef __cplusplus
}
#endif

#endif /* STEP_H */

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