| 1 | /* | 
| 2 | * Copyright (c) 2005 The University of Notre Dame. All Rights Reserved. | 
| 3 | * | 
| 4 | * The University of Notre Dame grants you ("Licensee") a | 
| 5 | * non-exclusive, royalty free, license to use, modify and | 
| 6 | * redistribute this software in source and binary code form, provided | 
| 7 | * that the following conditions are met: | 
| 8 | * | 
| 9 | * 1. Redistributions of source code must retain the above copyright | 
| 10 | *    notice, this list of conditions and the following disclaimer. | 
| 11 | * | 
| 12 | * 2. Redistributions in binary form must reproduce the above copyright | 
| 13 | *    notice, this list of conditions and the following disclaimer in the | 
| 14 | *    documentation and/or other materials provided with the | 
| 15 | *    distribution. | 
| 16 | * | 
| 17 | * This software is provided "AS IS," without a warranty of any | 
| 18 | * kind. All express or implied conditions, representations and | 
| 19 | * warranties, including any implied warranty of merchantability, | 
| 20 | * fitness for a particular purpose or non-infringement, are hereby | 
| 21 | * excluded.  The University of Notre Dame and its licensors shall not | 
| 22 | * be liable for any damages suffered by licensee as a result of | 
| 23 | * using, modifying or distributing the software or its | 
| 24 | * derivatives. In no event will the University of Notre Dame or its | 
| 25 | * licensors be liable for any lost revenue, profit or data, or for | 
| 26 | * direct, indirect, special, consequential, incidental or punitive | 
| 27 | * damages, however caused and regardless of the theory of liability, | 
| 28 | * arising out of the use of or inability to use software, even if the | 
| 29 | * University of Notre Dame has been advised of the possibility of | 
| 30 | * such damages. | 
| 31 | * | 
| 32 | * SUPPORT OPEN SCIENCE!  If you use OpenMD or its source code in your | 
| 33 | * research, please cite the appropriate papers when you publish your | 
| 34 | * work.  Good starting points are: | 
| 35 | * | 
| 36 | * [1]  Meineke, et al., J. Comp. Chem. 26, 252-271 (2005). | 
| 37 | * [2]  Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006). | 
| 38 | * [3]  Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008). | 
| 39 | * [4]  Kuang & Gezelter,  J. Chem. Phys. 133, 164101 (2010). | 
| 40 | * [5]  Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011). | 
| 41 | */ | 
| 42 |  | 
| 43 | /** | 
| 44 | * @file Torsion.hpp | 
| 45 | * @author    tlin | 
| 46 | * @date  11/01/2004 | 
| 47 | * @version 1.0 | 
| 48 | */ | 
| 49 |  | 
| 50 | #ifndef PRIMITIVES_TORSION_HPP | 
| 51 | #define PRIMITIVES_TORSION_HPP | 
| 52 |  | 
| 53 | #include "primitives/ShortRangeInteraction.hpp" | 
| 54 | #include "primitives/Atom.hpp" | 
| 55 | #include "types/TorsionType.hpp" | 
| 56 | #include <limits> | 
| 57 |  | 
| 58 | namespace OpenMD { | 
| 59 | struct TorsionData { | 
| 60 | RealType angle; | 
| 61 | RealType potential; | 
| 62 | }; | 
| 63 |  | 
| 64 | struct TorsionDataSet { | 
| 65 | RealType deltaV; | 
| 66 | TorsionData prev; | 
| 67 | TorsionData curr; | 
| 68 | }; | 
| 69 |  | 
| 70 |  | 
| 71 | /** | 
| 72 | * @class Torsion Torsion.hpp "types/Torsion.hpp" | 
| 73 | */ | 
| 74 | class Torsion : public ShortRangeInteraction { | 
| 75 | public: | 
| 76 | using ShortRangeInteraction::getValue; | 
| 77 | using ShortRangeInteraction::getPrevValue; | 
| 78 |  | 
| 79 | Torsion(Atom* atom1, Atom* atom2, Atom* atom3, Atom* atom4, TorsionType* tt); | 
| 80 | virtual ~Torsion() {} | 
| 81 | virtual void calcForce(RealType& angle, bool doParticlePot); | 
| 82 |  | 
| 83 | RealType getValue(int snapshotNo) { | 
| 84 | Vector3d pos1 = atoms_[0]->getPos(snapshotNo); | 
| 85 | Vector3d pos2 = atoms_[1]->getPos(snapshotNo); | 
| 86 | Vector3d pos3 = atoms_[2]->getPos(snapshotNo); | 
| 87 | Vector3d pos4 = atoms_[3]->getPos(snapshotNo); | 
| 88 |  | 
| 89 | Vector3d r21 = pos1 - pos2; | 
| 90 | Vector3d r32 = pos2 - pos3; | 
| 91 | Vector3d r43 = pos3 - pos4; | 
| 92 |  | 
| 93 | //  Calculate the cross products and distances | 
| 94 | Vector3d A = cross(r21, r32); | 
| 95 | RealType rA = A.length(); | 
| 96 | Vector3d B = cross(r32, r43); | 
| 97 | RealType rB = B.length(); | 
| 98 |  | 
| 99 | /* | 
| 100 | If either of the two cross product vectors is tiny, that means | 
| 101 | the three atoms involved are colinear, and the torsion angle is | 
| 102 | going to be undefined.  The easiest check for this problem is | 
| 103 | to use the product of the two lengths. | 
| 104 | */ | 
| 105 | if (rA * rB < OpenMD::epsilon) return numeric_limits<double>::quiet_NaN(); | 
| 106 |  | 
| 107 | A.normalize(); | 
| 108 | B.normalize(); | 
| 109 |  | 
| 110 | //  Calculate the sin and cos | 
| 111 | RealType cos_phi = dot(A, B) ; | 
| 112 | if (cos_phi > 1.0) cos_phi = 1.0; | 
| 113 | if (cos_phi < -1.0) cos_phi = -1.0; | 
| 114 | return acos(cos_phi); | 
| 115 | } | 
| 116 |  | 
| 117 |  | 
| 118 | RealType getPotential() { | 
| 119 | return potential_; | 
| 120 | } | 
| 121 |  | 
| 122 | Atom* getAtomA() { | 
| 123 | return atoms_[0]; | 
| 124 | } | 
| 125 |  | 
| 126 | Atom* getAtomB() { | 
| 127 | return atoms_[1]; | 
| 128 | } | 
| 129 |  | 
| 130 | Atom* getAtomC() { | 
| 131 | return atoms_[2]; | 
| 132 | } | 
| 133 |  | 
| 134 | Atom* getAtomD() { | 
| 135 | return atoms_[3]; | 
| 136 | } | 
| 137 |  | 
| 138 | TorsionType * getTorsionType() { | 
| 139 | return torsionType_; | 
| 140 | } | 
| 141 |  | 
| 142 | virtual std::string getName() { return name_;} | 
| 143 | /** Sets the name of this torsion for selections */ | 
| 144 | virtual void setName(const std::string& name) { name_ = name;} | 
| 145 |  | 
| 146 | void accept(BaseVisitor* v) { | 
| 147 | v->visit(this); | 
| 148 | } | 
| 149 |  | 
| 150 | protected: | 
| 151 |  | 
| 152 | TorsionType* torsionType_; | 
| 153 | std::string name_; | 
| 154 |  | 
| 155 | RealType potential_; | 
| 156 | }; | 
| 157 |  | 
| 158 | } | 
| 159 | #endif //PRIMITIVES_TORSION_HPP |