Commit f80c527b authored by julient31's avatar julient31
Browse files

Commit JT 100619 

- modified precession and Langevin/spin
parent 816546d0

src/SPIN/compute_spin.cpp

+2 −1
Original line number Diff line number Diff line
@@ -104,7 +104,8 @@ void ComputeSpin::compute_vector() 
        mag[0] += sp[i][0];

        mag[1] += sp[i][1];

        mag[2] += sp[i][2];

        magenergy -= 2.0*(sp[i][0]*fm[i][0] + sp[i][1]*fm[i][1] + sp[i][2]*fm[i][2]);

        // magenergy -= 2.0*(sp[i][0]*fm[i][0] + sp[i][1]*fm[i][1] + sp[i][2]*fm[i][2]);

        magenergy -= (sp[i][0]*fm[i][0] + sp[i][1]*fm[i][1] + sp[i][2]*fm[i][2]);

        tx = sp[i][1]*fm[i][2]-sp[i][2]*fm[i][1];

        ty = sp[i][2]*fm[i][0]-sp[i][0]*fm[i][2];

        tz = sp[i][0]*fm[i][1]-sp[i][1]*fm[i][0];

src/SPIN/fix_langevin_spin.cpp

+14 −12
Original line number Diff line number Diff line
@@ -30,7 +30,8 @@ 
#include "math_const.h"

#include "memory.h"

#include "modify.h"

#include "random_park.h"

// #include "random_park.h"

#include "random_mars.h"

#include "respa.h"

#include "update.h"

#include "utils.h"
@@ -74,7 +75,8 @@ FixLangevinSpin::FixLangevinSpin(LAMMPS *lmp, int narg, char **arg) : 


  // initialize Marsaglia RNG with processor-unique seed



  random = new RanPark(lmp,seed + comm->me);

  // random = new RanPark(lmp,seed + comm->me);

  random = new RanMars(lmp,seed + comm->me);



}
@@ -82,8 +84,6 @@ FixLangevinSpin::FixLangevinSpin(LAMMPS *lmp, int narg, char **arg) : 


FixLangevinSpin::~FixLangevinSpin()

{

  memory->destroy(spi);

  memory->destroy(fmi);

  delete random;

}
@@ -113,15 +113,14 @@ void FixLangevinSpin::init() 
  }

  if (flag_force >= flag_lang) error->all(FLERR,"Fix langevin/spin has to come after all other spin fixes");



  memory->create(spi,3,"langevin:spi");

  memory->create(fmi,3,"langevin:fmi");



  gil_factor = 1.0/(1.0+(alpha_t)*(alpha_t));

  dts = update->dt;

  dts = 0.25 * update->dt;



  double hbar = force->hplanck/MY_2PI;  // eV/(rad.THz)

  double kb = force->boltz;             // eV/K

  D = (MY_2PI*alpha_t*gil_factor*kb*temp);

  // D = (MY_2PI*alpha_t*gil_factor*kb*temp);

  D = (1.0/MY_2PI)*(MY_2PI*alpha_t*gil_factor*kb*temp);

  // D = (12.0/MY_2PI)*(MY_2PI*alpha_t*gil_factor*kb*temp);

  D /= (hbar*dts);

  sigma = sqrt(2.0*D);

}
@@ -157,9 +156,12 @@ void FixLangevinSpin::add_tdamping(double spi[3], double fmi[3]) 
void FixLangevinSpin::add_temperature(double fmi[3])

{



  double rx = sigma*(2.0*random->uniform() - 1.0);

  double ry = sigma*(2.0*random->uniform() - 1.0);

  double rz = sigma*(2.0*random->uniform() - 1.0);

  // double rx = sigma*(2.0*random->uniform() - 1.0);

  // double ry = sigma*(2.0*random->uniform() - 1.0);

  // double rz = sigma*(2.0*random->uniform() - 1.0);

  double rx = sigma*random->gaussian();

  double ry = sigma*random->gaussian();

  double rz = sigma*random->gaussian();



  // adding the random field

src/SPIN/fix_langevin_spin.h

+5 −5
Original line number Diff line number Diff line
@@ -32,12 +32,11 @@ class FixLangevinSpin : public Fix { 
  void init();

  void setup(int);

  void post_force_respa(int, int, int);

  void add_tdamping(double spi[3], double fmi[3]);      // add transverse damping

  void add_temperature(double fmi[3]);                  // add temperature

  void add_tdamping(double *, double *);                 // add transverse damping

  void add_temperature(double *);                        // add temperature

  int tdamp_flag, ldamp_flag, temp_flag;                 // damping and temperature flags



 protected:

  double *spi, *fmi;

  double alpha_t;               // transverse mag. damping

  double dts;                   // magnetic timestep

  double temp;                  // spin bath temperature
@@ -48,7 +47,8 @@ class FixLangevinSpin : public Fix { 
  class Compute *temperature;



  int nlevels_respa;

  class RanPark *random;

  // class RanPark *random;

  class RanMars *random;

  int seed;



};

src/SPIN/fix_precession_spin.cpp

+8 −4
Original line number Diff line number Diff line
@@ -257,7 +257,8 @@ void FixPrecessionSpin::post_force(int /* vflag */) 


      if (zeeman_flag) {          // compute Zeeman interaction

        compute_zeeman(i,fmi);

        epreci -= 2.0*hbar*(spi[0]*fmi[0] + spi[1]*fmi[1] + spi[2]*fmi[2]);

        // epreci -= 2.0*hbar*(spi[0]*fmi[0] + spi[1]*fmi[1] + spi[2]*fmi[2]);

        epreci -= hbar*(spi[0]*fmi[0] + spi[1]*fmi[1] + spi[2]*fmi[2]);

      }



      if (aniso_flag) {           // compute magnetic anisotropy
@@ -295,9 +296,12 @@ void FixPrecessionSpin::compute_single_precession(int i, double spi[3], double f 
void FixPrecessionSpin::compute_zeeman(int i, double fmi[3])

{

  double **sp = atom->sp;

  fmi[0] += 0.5*sp[i][3]*hx;

  fmi[1] += 0.5*sp[i][3]*hy;

  fmi[2] += 0.5*sp[i][3]*hz;

  // fmi[0] += 0.5*sp[i][3]*hx;

  // fmi[1] += 0.5*sp[i][3]*hy;

  // fmi[2] += 0.5*sp[i][3]*hz;

  fmi[0] += sp[i][3]*hx;

  fmi[1] += sp[i][3]*hy;

  fmi[2] += sp[i][3]*hz;

}



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

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