mdtools/md_code/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:	10
Committed:	Tue Jul 9 18:40:59 2002 UTC (23 years, 3 months ago) by mmeineke
Original Path:	*branches/mmeineke/mdtools/md_code/TorsionExtensions.cpp*
File size:	627 byte(s)
Log Message:	everything you need to make libmdtools
#	User	Rev	Content
1	mmeineke	10	#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			}