OOPSE-1.0/libmdtools/TorsionExtensions.cpp

#include "SRI.hpp"

CubicTorsion::CubicTorsion( Atom &a, Atom &b, Atom &c, Atom &d ){

  set_atoms( a, b, c, d );
  k1 = 0.0;
  k2 = 0.0;
  k3 = 0.0;
  k4 = 0.0;
}

void CubicTorsion::setConstants( double the_k1, double the_k2, double the_k3,
                                 double the_k4 ){
  
  k1 = the_k1;
  k2 = the_k2;
  k3 = the_k3;
  k4 = the_k4;
}

double CubicTorsion::torsion_force( double cos_phi ){
  
  double cp, cp2, cp3;
  double force;
  
  cp = cos_phi;
  cp2 = cp * cp;
  cp3 = cp2 * cp;

  c_potential_E = ( k1 * cp3 ) + ( k2 * cp2 ) + ( k3 * cp ) + k4;

  force = -( ( 3.0 * k1 * cp2 ) + ( 2.0 * k2 * cp ) + k3 );
  return force;
}
Revision:	1334
Committed:	Fri Jul 16 18:58:03 2004 UTC (19 years, 11 months ago) by gezelter
File size:	627 byte(s)
Log Message:	Initial import of OOPSE-1.0 source tree
#	Content
1	#include "SRI.hpp"
2
3	CubicTorsion::CubicTorsion( Atom &a, Atom &b, Atom &c, Atom &d ){
4
5	set_atoms( a, b, c, d );
6	k1 = 0.0;
7	k2 = 0.0;
8	k3 = 0.0;
9	k4 = 0.0;
10	}
11
12	void CubicTorsion::setConstants( double the_k1, double the_k2, double the_k3,
13	double the_k4 ){
14
15	k1 = the_k1;
16	k2 = the_k2;
17	k3 = the_k3;
18	k4 = the_k4;
19	}
20
21	double CubicTorsion::torsion_force( double cos_phi ){
22
23	double cp, cp2, cp3;
24	double force;
25
26	cp = cos_phi;
27	cp2 = cp * cp;
28	cp3 = cp2 * cp;
29
30	c_potential_E = ( k1 * cp3 ) + ( k2 * cp2 ) + ( k3 * cp ) + k4;
31
32	force = -( ( 3.0 * k1 * cp2 ) + ( 2.0 * k2 * cp ) + k3 );
33	return force;
34	}