src/primitives/Bend.cpp

#include "primitives/Bend.hpp"

namespace oopse {

/**@todo still a lot left to improve*/
void Bend::calcForce() {
    Vector3d pos1 = atom1_->getPos();
    Vector3d pos2 = atom2_->getPos();
    Vector3d pos3 = atom3_->getPos();

    Vector3d r21 = pos1 - pos2;
    double d21 = r21.length();

    double d21inv = 1.0 / d21;

    Vector3d r23 = pos3 - pos2;
    double d23 = r23.length();

    double d23inv = 1.0 / d23;

    double cosTheta = dot(r21, r23) / (d21 * d23);

    //check roundoff     
    if (cosTheta > 1.0) {
        cosTheta = 1.0;
    } else if (cosTheta < -1.0) {
        cosTheta = -1.0;
    }

    double theta = acos(cosTheta);

    double dVdTheta;

    bendType_->calcForce(theta, potential_, dVdTheta);

    double sinTheta = sqrt(1.0 - cosTheta * cosTheta);

    if (fabs(sinTheta) < 1.0E-6) {
        sinTheta = 1.0E-6;
    }

    double commonFactor1 = dVdTheta / sinTheta * d21inv;
    double commonFactor2 = dVdTheta / sinTheta * d23inv;

    Vector3d force1 = commonFactor1 * (r23 * d23inv - r21*d21inv*cosTheta);
    Vector3d force3 = commonFactor2 * (r21 * d21inv - r23*d23inv*cosTheta);

    //total force in current bend is zero
    Vector3d force2 = force1 + force3;
    force2 *= -1.0;

    atom1_->addFrc(force1);
    atom2_->addFrc(force2);
    atom3_->addFrc(force3);
}

} //end namespace oopse
Revision:	1857
Committed:	Mon Dec 6 20:15:02 2004 UTC (19 years, 8 months ago) by tim
File size:	1336 byte(s)
Log Message:	short range interaction for butane is correct.Still something wrong with long range one
#	User	Rev	Content
1	tim	1746	#include "primitives/Bend.hpp"
2
3			namespace oopse {
4
5			/*@todo still a lot left to improve/
6			void Bend::calcForce() {
7			Vector3d pos1 = atom1_->getPos();
8			Vector3d pos2 = atom2_->getPos();
9			Vector3d pos3 = atom3_->getPos();
10
11	tim	1857	Vector3d r21 = pos1 - pos2;
12			double d21 = r21.length();
13	tim	1746
14	tim	1857	double d21inv = 1.0 / d21;
15	tim	1746
16	tim	1857	Vector3d r23 = pos3 - pos2;
17			double d23 = r23.length();
18	tim	1746
19	tim	1857	double d23inv = 1.0 / d23;
20	tim	1746
21	tim	1857	double cosTheta = dot(r21, r23) / (d21 * d23);
22	tim	1746
23			//check roundoff
24			if (cosTheta > 1.0) {
25			cosTheta = 1.0;
26			} else if (cosTheta < -1.0) {
27			cosTheta = -1.0;
28			}
29
30			double theta = acos(cosTheta);
31
32	tim	1857	double dVdTheta;
33	tim	1746
34	tim	1857	bendType_->calcForce(theta, potential_, dVdTheta);
35	tim	1746
36			double sinTheta = sqrt(1.0 - cosTheta * cosTheta);
37
38	tim	1857	if (fabs(sinTheta) < 1.0E-6) {
39			sinTheta = 1.0E-6;
40	tim	1746	}
41
42	tim	1857	double commonFactor1 = dVdTheta / sinTheta * d21inv;
43			double commonFactor2 = dVdTheta / sinTheta * d23inv;
44	tim	1746
45	tim	1857	Vector3d force1 = commonFactor1 * (r23 * d23inv - r21d21invcosTheta);
46			Vector3d force3 = commonFactor2 * (r21 * d21inv - r23d23invcosTheta);
47	tim	1746
48			//total force in current bend is zero
49			Vector3d force2 = force1 + force3;
50			force2 *= -1.0;
51
52			atom1_->addFrc(force1);
53			atom2_->addFrc(force2);
54			atom3_->addFrc(force3);
55			}
56
57			} //end namespace oopse