void laser_rescale_2()
/* Instead of just rescaling, add the momentum increment in random direction.
Only thereafter rescale so the right amount of energy gets absorbed.
Involves several square roots, probably slower
*/
{
real exp_gauss_time_etc, gauss_time_squared, gauss_time_squared1;
int k;
gauss_time_squared = timestep * steps - laser_t_0;
gauss_time_squared *= gauss_time_squared;
exp_gauss_time_etc = exp(-gauss_time_squared/laser_sigma_t_squared/2.0)
* laser_p_peak * timestep * laser_atom_vol;
if (laser_t_1>0) {
gauss_time_squared1 = timestep * steps - laser_t_1;
gauss_time_squared1 *= gauss_time_squared1;
exp_gauss_time_etc += exp(-gauss_time_squared1/laser_sigma_t1_squared/2.0)
* laser_p_peak1 * timestep * laser_atom_vol;
}
for (k=0; k<NCELLS; k++) {
cell *p;
p = CELLPTR(k);
int i;
for (i=0; i < p->n; i++) {
real p_0_square; /* square of initial atom momentum */
real p_0;
real de; /* Kinetic energy to be added to the atom */
real dp;
real depth; /* Distance from origin along laser_dir */
real tmpx, tmpy, tmpsqr;
#ifndef TWOD
real tmpz;
#endif
real scale_p; /* Scale factor for atom momentum */
p_0_square = SPRODN(IMPULS,p,i,IMPULS,p,i);
p_0=sqrt(p_0_square);
depth = laser_calc_depth(p,i);
#ifdef LASERYZ /* spacial dependence of laser beam */
double x = ORT(p,i,X);
double y = ORT(p,i,Y);
double z = ORT(p,i,Z);
de = exp( -laser_mu*depth ) * exp_gauss_time_etc * laser_intensity_profile(x,y,z);
#else
de = exp(-laser_mu*depth) * exp_gauss_time_etc;
#endif
dp = sqrt( p_0_square + 2*de*MASSE(p,i) ) - p_0;
/* Momentum increment is to point in a random direction... */
#ifndef TWOD
rand_uvec_3d(&tmpx, &tmpy, &tmpz);
#else
rand_uvec_2d(&tmpx, &tmpy);
#endif
IMPULS(p,i,X) += tmpx * dp;
IMPULS(p,i,Y) += tmpy * dp;
#ifndef TWOD
IMPULS(p,i,Z) += tmpz * dp;
#endif
/* rescale present momentum to an absolute value of dp + p_0 */
scale_p = (p_0 + dp) / SQRT( SPRODN(IMPULS,p,i,IMPULS,p,i) );
IMPULS(p,i,X) *= scale_p;
IMPULS(p,i,Y) *= scale_p;
#ifndef TWOD
IMPULS(p,i,Z) *= scale_p;
#endif
}
}
} /* void laser_rescale_2()*/
void maxwell(real temp)
{
int k;
vektor tot_impuls;
int nactive_x, nactive_y, nactive_z;
static long dummy = 0;
int slice;
#ifdef DAMP
real tmp1,tmp2,tmp3,f,maxax,maxax2;
#endif
#ifdef LASER
real depth;
#endif
#ifdef UNIAX
real xisq;
real xi0;
real xi1;
real xi2;
real dot;
real norm;
real osq;
#endif
real TEMP;
real scale, xx, tmp;
int num, nhalf, typ;
TEMP = temp;
tot_impuls.x = 0.0; nactive_x = 0;
tot_impuls.y = 0.0; nactive_y = 0;
#ifndef TWOD
tot_impuls.z = 0.0; nactive_z = 0;
#endif
/* set temperature */
for (k=0; k<NCELLS; ++k) {
int i;
cell *p;
vektor *rest;
p = CELLPTR(k);
for (i=0; i<p->n; ++i) {
#ifdef LASER
depth = laser_dir.x * ORT(p,i,X)
+ laser_dir.y * ORT(p,i,Y)
#ifndef TWOD
+ laser_dir.z * ORT(p,i,Z)
#endif
;
depth -= laser_offset;
if (depth < 0) {
depth=0; /* we don't want to exceed laser_delta_temp */
}
TEMP = laser_delta_temp * exp(-laser_mu * depth);
TEMP += temperature; /* add base temperature of sample */
#endif /* LASER */
#ifdef DAMP
/* Calculate stadium function f */
maxax = MAX(MAX(stadium.x,stadium.y),stadium.z);
maxax2 = MAX(MAX(stadium2.x,stadium2.y),stadium2.z);
tmp1 = (stadium2.x == 0) ? 0 : SQR((ORT(p,i,X)-center.x)/(2.0*stadium2.x));
tmp2 = (stadium2.y == 0) ? 0 : SQR((ORT(p,i,Y)-center.y)/(2.0*stadium2.y));
tmp3 = (stadium2.z == 0) ? 0 : SQR((ORT(p,i,Z)-center.z)/(2.0*stadium2.z));
f = (tmp1+tmp2+tmp3-SQR(maxax/(2.0*maxax2)))/\
(.25- SQR(maxax/(2.0*maxax2)));
if (f<= 0.0)
f = 0.0;
else if (f>1.0)
f = 1.0;
/* we smooth the stadium function: to get a real bath tub !
fully damped atoms have temp=0, temperature gradient determined
by bath tub */
if (f !=0)
TEMP = damptemp * (1.0 - 0.5 * (1 + sin(-M_PI/2.0 + M_PI*f)));
else TEMP= temp;
#endif
#ifdef FTG
/* calc slice and set TEMP */
tmp = ORT(p,i,X) / box_x.x;
slice = (int) nslices * tmp;
if (slice<0) slice = 0;
if (slice>=nslices) slice = nslices -1;;
TEMP= Tleft + (Tright-Tleft)*(slice-nslices_Left+1) /
(real) (nslices-nslices_Left-nslices_Right+1);
if (slice>=nslices-nslices_Right) TEMP = Tright;
if (slice<nslices_Left) TEMP= Tleft;
#endif
tmp = sqrt(TEMP * MASSE(p,i));
rest = restrictions + VSORTE(p,i);
#ifndef RIGID
IMPULS(p,i,X) = imd_gaussian(tmp) * rest->x;
IMPULS(p,i,Y) = imd_gaussian(tmp) * rest->y;
#ifndef TWOD
IMPULS(p,i,Z) = imd_gaussian(tmp) * rest->z;
#endif
#else
/* superatoms get velocity zero */
if (superatom[VSORTE(p,i)]>-1) {
IMPULS(p,i,X) = 0.0;
IMPULS(p,i,Y) = 0.0;
#ifndef TWOD
IMPULS(p,i,Z) = 0.0;
#endif
}
#endif
nactive_x += (int) rest->x;
nactive_y += (int) rest->y;
#ifndef TWOD
nactive_z += (int) rest->z;
#endif
tot_impuls.x += IMPULS(p,i,X);
tot_impuls.y += IMPULS(p,i,Y);
#ifndef TWOD
tot_impuls.z += IMPULS(p,i,Z);
#endif
#ifdef UNIAX
/* angular velocities for uniaxial molecules */
/* choose a random vector in space */
do {
xi1 = 2.0 * drand48() - 1.0 ;
xi2 = 2.0 * drand48() - 1.0 ;
xisq = xi1 * xi1 + xi2 * xi2 ;
} while ( xisq >= 1.0 );
xi0 = sqrt( 1.0 - xisq ) ;
DREH_IMPULS(p,i,X) = 2.0 * xi1 * xi0 ;
DREH_IMPULS(p,i,Y) = 2.0 * xi2 * xi0 ;
DREH_IMPULS(p,i,Z) = 1.0 - 2.0 * xisq ;
/* constrain the vector to be perpendicular to the molecule */
dot = SPRODN(DREH_IMPULS,p,i,ACHSE,p,i);
DREH_IMPULS(p,i,X) -= dot * ACHSE(p,i,X) ;
DREH_IMPULS(p,i,Y) -= dot * ACHSE(p,i,Y) ;
DREH_IMPULS(p,i,Z) -= dot * ACHSE(p,i,Z) ;
/* renormalize vector */
osq = SPRODN(DREH_IMPULS,p,i,DREH_IMPULS,p,i);
norm = SQRT( osq );
DREH_IMPULS(p,i,X) /= norm ;
DREH_IMPULS(p,i,Y) /= norm ;
DREH_IMPULS(p,i,Z) /= norm ;
/* choose the magnitude of the angular momentum */
osq = - 2.0 * uniax_inert * TEMP * log( drand48() ) ;
norm = sqrt( osq );
DREH_IMPULS(p,i,X) *= norm ;
DREH_IMPULS(p,i,Y) *= norm ;
DREH_IMPULS(p,i,Z) *= norm ;
#endif /* UNIAX */
#ifdef SHOCK
/* plate against bulk */
if (shock_mode == 1) {
if ( ORT(p,i,X) < shock_strip )
IMPULS(p,i,X) += shock_speed * MASSE(p,i);
}
/* two halves against one another */
if (shock_mode == 2) {
if ( ORT(p,i,X) < box_x.x*0.5 )
IMPULS(p,i,X) += shock_speed * MASSE(p,i);
else
IMPULS(p,i,X) -= shock_speed * MASSE(p,i);
}
/* bulk against wall */
if (shock_mode == 3) IMPULS(p,i,X) += shock_speed * MASSE(p,i);
#endif
}
}
#ifdef CLONE
/* compute the total momentum afresh */
tot_impuls.x = 0.0;
tot_impuls.y = 0.0;
#ifndef TWOD
tot_impuls.z = 0.0;
#endif
/* set velocities of clones equal */
for (k=0; k<NCELLS; k++) {
int i, j;
cell *p;
p = CELLPTR(k);
for (i=0; i<p->n; i+=nclones) {
tot_impuls.x += nclones * IMPULS(p,i,X);
tot_impuls.y += nclones * IMPULS(p,i,Y);
#ifndef TWOD
tot_impuls.z += nclones * IMPULS(p,i,Z);
#endif
for (j=1; j<nclones; j++) {
IMPULS(p,i+j,X) = IMPULS(p,i,X);
IMPULS(p,i+j,Y) = IMPULS(p,i,Y);
#ifndef TWOD
IMPULS(p,i+j,Z) = IMPULS(p,i,Z);
#endif
}
}
}
#endif /* CLONE */
tot_impuls.x = nactive_x == 0 ? 0.0 : tot_impuls.x / nactive_x;
tot_impuls.y = nactive_y == 0 ? 0.0 : tot_impuls.y / nactive_y;
#ifndef TWOD
tot_impuls.z = nactive_z == 0 ? 0.0 : tot_impuls.z / nactive_z;
#endif
/* correct center of mass momentum */
for (k=0; k<NCELLS; ++k) {
int i;
cell *p;
vektor *rest;
p = CELLPTR(k);
for (i=0; i<p->n; ++i) {
rest = restrictions + VSORTE(p,i);
IMPULS(p,i,X) -= tot_impuls.x * rest->x;
IMPULS(p,i,Y) -= tot_impuls.y * rest->y;
#ifndef TWOD
IMPULS(p,i,Z) -= tot_impuls.z * rest->z;
#endif
}
}
}
void laser_rescale_1()
{ /* Rescale all atom velocities so that exactly the same amount of
kinetic energy is added to the atoms at a given depth.
The direction of the momentum vectors remains unchanged, except for
zero-velocity atoms, which will be given a random direction.*/
real exp_gauss_time_etc, gauss_time_squared, gauss_time_squared1;
int k;
real cosph, sinph, theta, costh, sinth;
gauss_time_squared = timestep * steps - laser_t_0;
gauss_time_squared *= gauss_time_squared;
exp_gauss_time_etc = exp(-gauss_time_squared/laser_sigma_t_squared/2.0)
* laser_p_peak * timestep * laser_atom_vol;
if (laser_t_1>0) {
gauss_time_squared1 = timestep * steps - laser_t_1;
gauss_time_squared1 *= gauss_time_squared1;
exp_gauss_time_etc += exp(-gauss_time_squared1/laser_sigma_t1_squared/2.0)
* laser_p_peak1 * timestep * laser_atom_vol;
}
for (k=0; k<NCELLS; k++) {
cell *p;
p = CELLPTR(k);
int i;
for (i=0; i < p->n; i++) {
real p_0_square; /* square of initial atom momentum */
real de; /* Kinetic energy to be added to the atom */
real depth; /* Distance from origin along laser_dir */
real tmpx, tmpy, tmpsqr;
#ifndef TWOD
real tmpz;
#endif
real scale_p; /* Scale factor for atom momentum */
p_0_square = SPRODN(IMPULS,p,i,IMPULS,p,i);
depth = laser_calc_depth(p,i);
#ifdef PDECAY
if( ORT(p,i,X) > ramp_start )
{
switch ( pdecay_mode){
case 0:
{
/* y= m * x + b */
double m = 1 / ( (ramp_end - ramp_start ) ) ;
double b = - ramp_start / ( ramp_end - ramp_start );
double xia = ORT(p,i,X) *m + b ;
IMPULS(p,i,X) *= 1.0 - ( ORT(p,i,X) *m + b) ;
if(steps==-1)
printf(" %f %f \n", ORT(p,i,X),1.0 - ( ORT(p,i,X) * m + b) );
break;
}
case 1:
{
double a = 1.0 / ( ramp_start - ramp_end);
a *= a;
IMPULS(p,i,X) *= a * ( ORT(p,i,X) - ramp_end ) * ( ORT(p,i,X) - ramp_end );
if(steps==-1)
printf("%f %f \n", ORT(p,i,X), a * ( ORT(p,i,X) - ramp_end ) * ( ORT(p,i,X) - ramp_end ));
break;
}
break;
case 2:
{
double m = 1 / ( (ramp_end - ramp_start ) ) ;
double b = - ramp_start / ( ramp_end - ramp_start );
KRAFT(p,i,X) -= ( IMPULS(p,i,X)/MASSE(p,i)) * ( ORT(p,i,X) *m + b ) * xipdecay;
if(steps==-1)
printf(" %f %f \n", ORT(p,i,X),ORT(p,i,X) *m + b);
break;
}
break;
case 3:
{
double a = 1.0 / ( ramp_end - ramp_start);
a *= a;
KRAFT(p,i,X) -= ( IMPULS(p,i,X)/MASSE(p,i)) * xipdecay * a * ( ORT(p,i,X) - ramp_start ) * ( ORT(p,i,X) - ramp_start );
if(steps==-1)
printf("%f %f \n", ORT(p,i,X), a * ( ORT(p,i,X) - ramp_start ) * ( ORT(p,i,X) - ramp_start ) );
break;
}
break;
default:
error("Illegal value for parameter pdecay_mode.\n");
break;
}
}
#endif
#ifdef LASERYZ /* spacial dependence of laser beam */
double x = ORT(p,i,X);
double y = ORT(p,i,Y);
double z = ORT(p,i,Z);
de = exp( -laser_mu*depth ) * exp_gauss_time_etc * laser_intensity_profile(x,y,z);
#else
de = exp(-laser_mu*depth) * exp_gauss_time_etc;
#endif
if ( p_0_square == 0.0 ) { /* we need a direction for the momentum. */
#ifndef TWOD
/* find random 3d unit vector */
rand_uvec_3d(&tmpx, &tmpy, &tmpz);
#else
/* find random 2d unit vector */
rand_uvec_2d(&tmpx, &tmpy);
#endif
scale_p = sqrt( de * 2.0 * MASSE(p,i) );
IMPULS(p,i,X) = tmpx * scale_p;
IMPULS(p,i,Y) = tmpy * scale_p;
#ifndef TWOD
IMPULS(p,i,Z) = tmpz * scale_p;
#endif
} else { /* rescale present momentum */
scale_p = sqrt( de * 2.0 * MASSE(p,i) / p_0_square + 1.0 );
IMPULS(p,i,X) *= scale_p;
IMPULS(p,i,Y) *= scale_p;
#ifndef TWOD
IMPULS(p,i,Z) *= scale_p;
#endif
}
}
}
} /* void laser_rescale_1()*/
