OpenMD  2.5
Molecular Dynamics in the Open
OpenMD::TrappeTorsionType Class Reference

#include "types/TrappeTorsionType.hpp"

Inheritance diagram for OpenMD::TrappeTorsionType:
OpenMD::PolynomialTorsionType OpenMD::TorsionType

Public Member Functions

 TrappeTorsionType (RealType c0, RealType c1, RealType c2, RealType c3, bool trans180)
- Public Member Functions inherited from OpenMD::PolynomialTorsionType
 PolynomialTorsionType ()
RealType getCoefficient (int power)
void addCoefficient (int power, RealType coefficient)
void setCoefficient (int power, RealType coefficient)
void setPolynomial (DoublePolynomial p)
virtual void calcForce (RealType cosPhi, RealType &V, RealType &dVdCosPhi)
- Public Member Functions inherited from OpenMD::TorsionType
virtual ~TorsionType ()

Private Attributes

RealType c0_
RealType c1_
RealType c2_
RealType c3_


std::ostream & operator<< (std::ostream &os, TrappeTorsionType &ttt)

Detailed Description

These torsion types are defined identically with functional form given in the following paper:

"Transferable Potentials for Phase Equilibria. 1. United-Atom Description of n-Alkanes," by Marcus G. Martin and J. Ilja Siepmann, J. Phys. Chem. B; 1998; 102(14) pp 2569 - 2577;

Also listed as type A torsions on this page:

This torsion potential has the form:

\[ V_{tors} = c_0 + c_1*(1+\cos(\phi)) + c_2*(1-\cos(2*\phi)) + c_3*(1+\cos(3*\phi)) \]


1) This is very similar to the OplsTorsionType with coefficients defined without the factor of 1/2, and an extra $c_0$ term.

2) Coefficients are assumed to be in kcal / mol, although the papers usually give the parameters in units of K.

Definition at line 86 of file TrappeTorsionType.hpp.

Constructor & Destructor Documentation

◆ TrappeTorsionType()

OpenMD::TrappeTorsionType::TrappeTorsionType ( RealType  c0,
RealType  c1,
RealType  c2,
RealType  c3,
bool  trans180 

Friends And Related Function Documentation

◆ operator<<

std::ostream& operator<< ( std::ostream &  os,
TrappeTorsionType ttt 

Definition at line 123 of file TrappeTorsionType.hpp.

Referenced by TrappeTorsionType().

Member Data Documentation

◆ c0_

RealType OpenMD::TrappeTorsionType::c0_

Definition at line 116 of file TrappeTorsionType.hpp.

Referenced by OpenMD::operator<<().

◆ c1_

RealType OpenMD::TrappeTorsionType::c1_

Definition at line 117 of file TrappeTorsionType.hpp.

Referenced by OpenMD::operator<<().

◆ c2_

RealType OpenMD::TrappeTorsionType::c2_

Definition at line 118 of file TrappeTorsionType.hpp.

Referenced by OpenMD::operator<<().

◆ c3_

RealType OpenMD::TrappeTorsionType::c3_

Definition at line 119 of file TrappeTorsionType.hpp.

Referenced by OpenMD::operator<<().

The documentation for this class was generated from the following file: