Merge pull request #1707 from charlessievers/lammps_gjf (e77e286d) · Commits · 郑智淋 / lammps

doc/src/fix_langevin.txt

+3 −3

Original line number	Diff line number	Diff line
		@@ -246,11 +246,11 @@ velocity given in "Gronbech-Jensen/Farago"_#Gronbech-Jensen; this velocity
		is shown to be systematically lower than the target temperature by a small
		amount, which grows quadratically with the timestep.
		The {gjf} option {vhalf} outputs the 2GJ half-step velocity given in
		"Gronbech Jensen/Gronbech-Jensen"_#2Gronbech-Jensen; this velocity is shown
		to not have any linear statistical errors for any stable time step.
		"Gronbech Jensen/Gronbech-Jensen"_#2Gronbech-Jensen; for linear systems,
		this velocity is shown to not have any statistical errors for any stable time step.
		An overview of statistically correct Boltzmann and Maxwell-Boltzmann
		sampling of true on-site and true half-step velocities is given in
		"Gronbech-Jensen_#1Gronbech-Jensen.
		"Gronbech-Jensen"_#1Gronbech-Jensen.
		Regardless of the choice of output velocity, the sampling of the configurational
		distribution of atom positions is the same, and linearly consistent with the
		target temperature.

+17 −8

Original line number	Diff line number	Diff line
		@@ -240,7 +240,7 @@ void FixLangevin::init()
		if (strcmp(id,modify->fix[i]->id) == 0) before = 0;
		else if ((modify->fmask[i] && utils::strmatch(modify->fix[i]->style,"^nve")) && before) flag = 1;
		}
		if (flag && comm->me == 0)
		if (flag)
		error->all(FLERR,"Fix langevin gjf should come before fix nve");
		}

		@@ -1007,12 +1007,21 @@ void FixLangevin::reset_dt()
		{
		if (atom->mass) {
		for (int i = 1; i <= atom->ntypes; i++) {
		if (gjfflag)
		gfactor2[i] = sqrt(atom->mass[i]) *
		sqrt(2.0*force->boltz/t_period/update->dt/force->mvv2e) /
		force->ftm2v;
		else
		gfactor2[i] = sqrt(atom->mass[i]) *
		sqrt(24.0*force->boltz/t_period/update->dt/force->mvv2e) /
		force->ftm2v;
		gfactor2[i] *= 1.0/sqrt(ratio[i]);
		}
		}
		if (gjfflag) {
		gjfa = (1.0-update->dt/2.0/t_period)/(1.0+update->dt/2.0/t_period);
		gjfsib = sqrt(1.0+update->dt/2.0/t_period);
		}
		}

		/* ---------------------------------------------------------------------- */