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fix_rattle.h
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Fri, Jun 28, 15:53

fix_rattle.h
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/* -*- c++ -*- ----------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#ifdef FIX_CLASS
FixStyle(rattle,FixRattle)
#else
#ifndef LMP_FIX_RATTLE_H
#define LMP_FIX_RATTLE_H
#include "fix.h"
#include "fix_shake.h"
namespace LAMMPS_NS {
class FixRattle : public FixShake {
public:
double **vp; // array for unconstrained velocities
double dtfv; // timestep for velocity update
int comm_mode; // mode for communication pack/unpack
FixRattle(class LAMMPS *, int, char **);
~FixRattle();
int setmask();
void init();
void post_force(int);
void post_force_respa(int, int, int);
void final_integrate();
void final_integrate_respa(int,int);
void coordinate_constraints_end_of_step();
double memory_usage();
void grow_arrays(int);
int pack_forward_comm(int, int *, double *, int, int *);
void unpack_forward_comm(int, int, double *);
void reset_dt();
private:
void update_v_half_nocons();
void update_v_half_nocons_respa(int);
void vrattle2(int m);
void vrattle3(int m);
void vrattle4(int m);
void vrattle3angle(int m);
void solve3x3exactly(const double a[][3], const double c[], double l[]);
void solve2x2exactly(const double a[][2], const double c[], double l[]);
// debugging methosd
bool check3angle(double ** v, int m, bool checkr, bool checkv);
bool check2(double **v, int m, bool checkr, bool checkv);
bool check3(double **v, int m, bool checkr, bool checkv);
bool check4(double **v, int m, bool checkr, bool checkv);
bool check_constraints(double **v, bool checkr, bool checkv);
void end_of_step();
};
}
#endif
#endif
/* ERROR/WARNING messages:
W: Fix rattle should come after all other integration fixes
This fix is designed to work after all other integration fixes change
atom positions. Thus it should be the last integration fix specified.
If not, it will not satisfy the desired constraints as well as it
otherwise would.
E: RATTLE determinant = 0.0
The determinant of the matrix being solved for a single cluster
specified by the fix rattle command is numerically invalid.
E: RATTLE failed
Certain constraints were not satisfied.
E: RATTLE coordinate constraints are not satisfied up to desired tolerance
Self-explanatory.
E: RATTLE velocity constraints are not satisfied up to desired tolerance
Self-explanatory.
*/

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