| 1 | #include "primitives/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 | } |