X-Git-Url: https://hackdaworld.org/gitweb/?a=blobdiff_plain;f=moldyn.c;h=e96cdd4bd66e32632087321d07d12173024bec24;hb=b040d775deb32173e6536464a3e2ad95a6a5bd55;hp=ba3c1a30c8c2bd995a2ac2264d9a79984db01015;hpb=706aed2512544b99ff34308fdb673b19ee884ce0;p=physik%2Fposic.git

diff --git a/moldyn.c b/moldyn.c
index ba3c1a3..e96cdd4 100644
--- a/moldyn.c
+++ b/moldyn.c
@@ -42,8 +42,8 @@ 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 +51,7 @@ 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 +63,38 @@ int create_lattice(unsigned char type,int element,double mass,double lc,
 	return ret;
 }
 
+int thermal_init(t_atom *atom,int count,double t) {
+
+	/*
+	 * - gaussian distribution of velocities
+	 * - velocity scaling (E = 3/2 N k T), E: kinetic energy
+	 */
+
+	int i;
+	double e,c,v;
+
+	e=.0;
+
+	for(i=0;i<count;i++) {
+		/* x direction */
+		v=gauss_rand();
+		atom[count].v.x=v;
+		e+=0.5*atom[count].mass*v*v;
+		/* y direction */
+		v=gauss_rand();
+		atom[count].v.y=v;
+		e+=0.5*atom[count].mass*v*v;
+		/* z direction */
+		v=gauss_rand();
+		atom[count].v.z=v;
+		e+=0.5*atom[count].mass*v*v;
+	}
+
+	c=sqrt((2.0*e)/(3.0*count*K_BOLTZMANN));
+
+	for(i=0;i<count;i++)
+		v3_scale(&(atom[count].v),&(atom[count].v),(1.0/c));
+
+	return 0;
+}
+