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 do_forces(cell *p, cell *q, vektor pbc, real *Epot, real *Virial,
real *Vir_xx, real *Vir_yy, real *Vir_zz,
real *Vir_yz, real *Vir_zx, real *Vir_xy)
{
int i, j ;
int jstart ;
real tmp_virial ;
vektor tmp_vir_vect ;
vektor tmp_r12 ;
vektor r12 ;
vektor e1 ;
vektor e2 ;
real rsqr ;
real pot12 ;
vektor force12 ;
vektor torque12 ;
vektor torque21 ;
/* actual pair virial and virial components */
tmp_virial = 0.0;
tmp_vir_vect.x = 0.0;
tmp_vir_vect.y = 0.0;
tmp_vir_vect.z = 0.0;
/* For each atom in first cell */
for (i = 0;i < p->n; ++i) {
/* For each atom in neighbouring cell */
/* Some compilers don't find the expressions that are invariant
to the inner loop. I'll have to define my own temp variables. */
tmp_r12.x = ORT(p,i,X) - pbc.x;
tmp_r12.y = ORT(p,i,Y) - pbc.y;
tmp_r12.z = ORT(p,i,Z) - pbc.z;
e1.x = ACHSE(p,i,X);
e1.y = ACHSE(p,i,Y);
e1.z = ACHSE(p,i,Z);
#ifdef TWOD
jstart = (((p==q) && (pbc.x==0) && (pbc.y==0)) ? i+1 : 0);
#else
jstart = (((p==q) && (pbc.x==0) && (pbc.y==0) && (pbc.z==0)) ? i+1 : 0);
#endif
for (j = jstart; j < q->n; ++j) {
/* Calculate distance */
r12.x = tmp_r12.x - ORT(q,j,X);
r12.y = tmp_r12.y - ORT(q,j,Y);
r12.z = tmp_r12.z - ORT(q,j,Z);
rsqr = SPROD(r12,r12);
e2.x = ACHSE(q,j,X);
e2.y = ACHSE(q,j,Y);
e2.z = ACHSE(q,j,Z);
#ifndef NODBG_DIST
if (0==rsqr)
{
char msgbuf[256];
sprintf(msgbuf,"Distance is zero: i=%d, j=%d\n",i,j);
error(msgbuf);
}
#else
if (0==rsqr) error("Distance is zero.");
#endif
if (rsqr <= uniax_r2_cut) {
/* calculate interactions, if distance smaller than cutoff radius */
gay_berne( r12, e1, e2, rsqr, uniax_sig, uniax_eps, &pot12,
&force12, &torque12, &torque21) ;
/* accumulate forces */
KRAFT(p,i,X) += force12.x;
KRAFT(p,i,Y) += force12.y;
KRAFT(p,i,Z) += force12.z;
KRAFT(q,j,X) -= force12.x;
KRAFT(q,j,Y) -= force12.y;
KRAFT(q,j,Z) -= force12.z;
/* accumulate torques */
DREH_MOMENT(p,i,X) += torque12.x;
DREH_MOMENT(p,i,Y) += torque12.y;
DREH_MOMENT(p,i,Z) += torque12.z;
DREH_MOMENT(q,j,X) += torque21.x;
DREH_MOMENT(q,j,Y) += torque21.y;
DREH_MOMENT(q,j,Z) += torque21.z;
*Epot += pot12;
pot12 *= 0.5; /* avoid double counting */
POTENG(p,i) += pot12;
POTENG(q,j) += pot12;
tmp_vir_vect.x += r12.x * force12.x ;
tmp_vir_vect.y += r12.y * force12.y ;
tmp_vir_vect.z += r12.z * force12.z ;
tmp_virial += r12.x * force12.x
+ r12.y * force12.y + r12.z * force12.z ;
}; /* if */
}; /* for j */
}; /* for i */
*Vir_xx += tmp_vir_vect.x;
*Vir_yy += tmp_vir_vect.y;
*Vir_zz += tmp_vir_vect.z;
*Virial += tmp_virial ;
} /* do_forces_uniax */
