vel scaling fixed/changed

[physik/posic.git] / moldyn.c

diff --git a/moldyn.c b/moldyn.c
index de7bbbf..d52fcd3 100644 (file)
--- a/moldyn.c
+++ b/moldyn.c
@@ -93,6 +93,13 @@ int set_dim(t_moldyn *moldyn,double x,double y,double z,u8 visualize) {
        return 0;
 }
 
+int set_nn_dist(t_moldyn *moldyn,double dist) {
+
+       moldyn->nnd=dist;
+
+       return 0;
+}
+
 int set_pbc(t_moldyn *moldyn,u8 x,u8 y,u8 z) {
 
        if(x)
@@ -221,6 +228,7 @@ int create_lattice(t_moldyn *moldyn,u8 type,double lc,int element,double mass,
        }
 
        moldyn->count=count;
+       printf("[moldyn] created lattice with %d atoms\n",count);
 
        while(count) {
                moldyn->atom[count-1].element=element;
@@ -311,15 +319,15 @@ int thermal_init(t_moldyn *moldyn) {
        }
 
        /* velocity scaling */
-       scale_velocity(moldyn);
+       scale_velocity(moldyn,VSCALE_INIT_EQUI);
 
        return 0;
 }
 
-int scale_velocity(t_moldyn *moldyn) {
+int scale_velocity(t_moldyn *moldyn,u8 type) {
 
        int i;
-       double e,c;
+       double e,scale;
        t_atom *atom;
 
        atom=moldyn->atom;
@@ -328,17 +336,14 @@ int scale_velocity(t_moldyn *moldyn) {
         * - velocity scaling (E = 3/2 N k T), E: kinetic energy
         */
 
-       if(moldyn->t==0.0) {
-               printf("[moldyn] no velocity scaling for T = 0 K\n");
-               return -1;
-       }
-
        e=0.0;
        for(i=0;i<moldyn->count;i++)
                e+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
-       c=sqrt((2.0*e)/(3.0*moldyn->count*K_BOLTZMANN*moldyn->t));
+       scale=(1.5*moldyn->count*K_BOLTZMANN*moldyn->t)/e;
+       if(type&VSCALE_INIT_EQUI) scale*=2.0; /* equipartition theorem */
+       scale=sqrt(scale);
        for(i=0;i<moldyn->count;i++)
-               v3_scale(&(atom[i].v),&(atom[i].v),(1.0/c));
+               v3_scale(&(atom[i].v),&(atom[i].v),scale);
 
        return 0;
 }
@@ -594,9 +599,9 @@ int moldyn_integrate(t_moldyn *moldyn) {
        t_3dvec p;
        t_moldyn_schedule *schedule;
        t_atom *atom;
-
        int fd;
        char fb[128];
+       double ds;
 
        schedule=&(moldyn->schedule);
        atom=moldyn->atom;
@@ -617,6 +622,17 @@ int moldyn_integrate(t_moldyn *moldyn) {
        /* calculate initial forces */
        potential_force_calc(moldyn);
 
+       /* do some checks before we actually start calculating bullshit */
+       if(moldyn->cutoff>0.5*moldyn->dim.x)
+               printf("[moldyn] warning: cutoff > 0.5 x dim.x\n");
+       if(moldyn->cutoff>0.5*moldyn->dim.y)
+               printf("[moldyn] warning: cutoff > 0.5 x dim.y\n");
+       if(moldyn->cutoff>0.5*moldyn->dim.z)
+               printf("[moldyn] warning: cutoff > 0.5 x dim.z\n");
+       ds=0.5*atom[0].f.x*moldyn->tau_square/atom[0].mass;
+       if(ds>0.05*moldyn->nnd)
+               printf("[moldyn] warning: forces too high / tau too small!\n");
+
        /* zero absolute time */
        moldyn->time=0.0;
 
@@ -758,7 +774,6 @@ int potential_force_calc(t_moldyn *moldyn) {
        moldyn->energy=0.0;
 
        for(i=0;i<count;i++) {
-printf("BAR %d %d\n",i,count);
        
                /* reset force */
                v3_zero(&(atom[i].f));