X-Git-Url: https://hackdaworld.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=moldyn.c;h=b507d65354dabcf690628bc8bc31846962542fe3;hb=3ffe2a08e25fc091b6241885055450009267e2d8;hp=ba3c1a30c8c2bd995a2ac2264d9a79984db01015;hpb=706aed2512544b99ff34308fdb673b19ee884ce0;p=physik%2Fposic.git

diff --git a/moldyn.c b/moldyn.c
index ba3c1a3..b507d65 100644
--- a/moldyn.c
+++ b/moldyn.c
@@ -9,9 +9,11 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
 
 #include "math/math.h"
 #include "init/init.h"
+#include "random/random.h"
 
 
 int create_lattice(unsigned char type,int element,double mass,double lc,
@@ -42,8 +44,8 @@ int create_lattice(unsigned char type,int element,double mass,double lc,
 			ret=diamond_init(a,b,c,lc,*atom,&origin);
 			break;
 		default:
-			ret=-1;
 			printf("unknown lattice type (%02x)\n",type);
+			return -1;
 	}
 
 	/* debug */
@@ -51,6 +53,7 @@ int create_lattice(unsigned char type,int element,double mass,double lc,
 		printf("ok, there is something wrong ...\n");
 		printf("calculated -> %d atoms\n",count);
 		printf("created -> %d atoms\n",ret);
+		return -1;
 	}
 
 	while(count) {
@@ -62,3 +65,83 @@ int create_lattice(unsigned char type,int element,double mass,double lc,
 	return ret;
 }
 
+int destroy_lattice(t_atom *atom) {
+
+	if(atom) free(atom);
+
+	return 0;
+}
+
+int thermal_init(t_atom *atom,t_random *random,int count,double t) {
+
+	/*
+	 * - gaussian distribution of velocities
+	 * - zero total momentum
+	 * - velocity scaling (E = 3/2 N k T), E: kinetic energy
+	 */
+
+	int i;
+	double v,sigma;
+	t_3dvec p_total,delta;
+
+	/* gaussian distribution of velocities */
+	v3_zero(&p_total);
+	for(i=0;i<count;i++) {
+		sigma=sqrt(2.0*K_BOLTZMANN*t/atom[count].mass);
+		/* x direction */
+		v=sigma*rand_get_gauss(random);
+		atom[count].v.x=v;
+		p_total.x+=atom[count].mass*v;
+		/* y direction */
+		v=sigma*rand_get_gauss(random);
+		atom[count].v.y=v;
+		p_total.x+=atom[count].mass*v;
+		/* z direction */
+		v=sigma*rand_get_gauss(random);
+		atom[count].v.z=v;
+		p_total.x+=atom[count].mass*v;
+	}
+
+	/* zero total momentum */
+	for(i=0;i<count;i++) {
+		v3_scale(&delta,&p_total,1.0/atom[count].mass);
+		v3_sub(&(atom[count].v),&(atom[count].v),&delta);
+	}
+
+	/* velocity scaling */
+	scale_velocity(atom,count,t);
+
+	return 0;
+}
+
+int scale_velocity(t_atom *atom,int count,double t) {
+
+	int i;
+	double e,c;
+
+	/*
+	 * - velocity scaling (E = 3/2 N k T), E: kinetic energy
+	 */
+	e=0.0;
+	for(i=0;i<count;i++)
+		e+=0.5*atom[count].mass*v3_absolute_square(&(atom[count].v));
+	c=sqrt((2.0*e)/(3.0*count*K_BOLTZMANN*t));
+	for(i=0;i<count;i++)
+		v3_scale(&(atom[count].v),&(atom[count].v),(1.0/c));
+
+	return 0;
+}
+
+double get_e_kin(t_atom *atom,int count) {
+
+	int i;
+	double e;
+
+	e=0.0;
+
+	for(i=0;i<count;i++)
+		e+=0.5*atom[count].mass*v3_absolute_square(&(atom[count].v));
+
+	return e;
+}
+