added fluctuation calc code

[physik/posic.git] / moldyn.c

diff --git a/moldyn.c b/moldyn.c
index cd2a803..16c811e 100644 (file)
--- a/moldyn.c
+++ b/moldyn.c
@@ -218,6 +218,14 @@ int set_potential_params(t_moldyn *moldyn,void *params) {
        return 0;
 }
 
+int set_mean_skip(t_moldyn *moldyn,int skip) {
+
+       printf("[moldyn] skip %d steps before starting average calc\n",skip);
+       moldyn->mean_skip=skip;
+
+       return 0;
+}
+
 int moldyn_set_log_dir(t_moldyn *moldyn,char *dir) {
 
        strncpy(moldyn->vlsdir,dir,127);
@@ -728,8 +736,12 @@ double temperature_calc(t_moldyn *moldyn) {
        /* assume up to date kinetic energy, which is 3/2 N k_B T */
 
        moldyn->t=(2.0*moldyn->ekin)/(3.0*K_BOLTZMANN*moldyn->count);
+
+       if(moldyn->total_steps<moldyn->mean_skip)
+               return 0;
+
        moldyn->t_sum+=moldyn->t;
-       moldyn->mean_t=moldyn->t_sum/moldyn->total_steps;
+       moldyn->mean_t=moldyn->t_sum/(moldyn->total_steps+1-moldyn->mean_skip);
 
        return moldyn->t;
 }
@@ -826,41 +838,54 @@ double pressure_calc(t_moldyn *moldyn) {
 
        /* virial sum and mean virial */
        moldyn->virial_sum+=v;
-       moldyn->mean_v=moldyn->virial_sum/moldyn->total_steps;
+       if(moldyn->total_steps>=moldyn->mean_skip)
+               moldyn->mean_v=moldyn->virial_sum/
+                              (moldyn->total_steps+1-moldyn->mean_skip);
 
        /* assume up to date kinetic energy */
        moldyn->p=2.0*moldyn->ekin+moldyn->mean_v;
        moldyn->p/=(3.0*moldyn->volume);
-       moldyn->p_sum+=moldyn->p;
-       moldyn->mean_p=moldyn->p_sum/moldyn->total_steps;
+       if(moldyn->total_steps>=moldyn->mean_skip) {
+               moldyn->p_sum+=moldyn->p;
+               moldyn->mean_p=moldyn->p_sum/
+                              (moldyn->total_steps+1-moldyn->mean_skip);
+       }
 
        /* pressure from 'absolute coordinates' virial */
        virial=&(moldyn->virial);
        v=virial->xx+virial->yy+virial->zz;
        moldyn->gp=2.0*moldyn->ekin+v;
        moldyn->gp/=(3.0*moldyn->volume);
-       moldyn->gp_sum+=moldyn->gp;
-       moldyn->mean_gp=moldyn->gp_sum/moldyn->total_steps;
+       if(moldyn->total_steps>=moldyn->mean_skip) {
+               moldyn->gp_sum+=moldyn->gp;
+               moldyn->mean_gp=moldyn->gp_sum/
+                              (moldyn->total_steps+1-moldyn->mean_skip);
+       }
 
        return moldyn->p;
 }
 
 int energy_fluctuation_calc(t_moldyn *moldyn) {
 
+       if(moldyn->total_steps<moldyn->mean_skip)
+               return 0;
+
        /* assume up to date energies */
 
        /* kinetic energy */
        moldyn->k_sum+=moldyn->ekin;
        moldyn->k2_sum+=(moldyn->ekin*moldyn->ekin);
-       moldyn->k_mean=moldyn->k_sum/moldyn->total_steps;
-       moldyn->k2_mean=moldyn->k2_sum/moldyn->total_steps;
+       moldyn->k_mean=moldyn->k_sum/(moldyn->total_steps+1-moldyn->mean_skip);
+       moldyn->k2_mean=moldyn->k2_sum/
+                       (moldyn->total_steps+1-moldyn->mean_skip);
        moldyn->dk2_mean=moldyn->k2_mean-(moldyn->k_mean*moldyn->k_mean);
 
        /* potential energy */
        moldyn->v_sum+=moldyn->energy;
        moldyn->v2_sum+=(moldyn->energy*moldyn->energy);
-       moldyn->v_mean=moldyn->v_sum/moldyn->total_steps;
-       moldyn->v2_mean=moldyn->v2_sum/moldyn->total_steps;
+       moldyn->v_mean=moldyn->v_sum/(moldyn->total_steps+1-moldyn->mean_skip);
+       moldyn->v2_mean=moldyn->v2_sum/
+                       (moldyn->total_steps+1-moldyn->mean_skip);
        moldyn->dv2_mean=moldyn->v2_mean-(moldyn->v_mean*moldyn->v_mean);
 
        return 0;
@@ -870,6 +895,10 @@ int get_heat_capacity(t_moldyn *moldyn) {
 
        double temp2,ighc;
 
+       /* averages needed for heat capacity calc */
+       if(moldyn->total_steps<moldyn->mean_skip)
+               return 0;
+
        /* (temperature average)^2 */
        temp2=moldyn->mean_t*moldyn->mean_t;
        printf("[moldyn] specific heat capacity for T=%f K [J/(kg K)]\n",
@@ -890,6 +919,7 @@ int get_heat_capacity(t_moldyn *moldyn) {
 
        printf("  NVE: %f\n",moldyn->c_v_nve*KILOGRAM/JOULE);
        printf("  NVT: %f\n",moldyn->c_v_nvt*KILOGRAM/JOULE);
+printf("  --> <dV2> sim: %f experimental: %f\n",moldyn->dv2_mean,1.5*moldyn->count*K_B2*moldyn->mean_t*moldyn->mean_t*(1.0-1.5*moldyn->count*K_BOLTZMANN/(700*moldyn->mass*JOULE/KILOGRAM)));
 
        return 0;
 }