* Get the nonbonded force parameters for a particle.
*
* @param index the index of the particle for which to get parameters
* @param charge the charge of the particle, measured in units of the proton charge
* @param sigma the sigma parameter of the Lennard-Jones potential (corresponding to the van der Waals radius of the particle), measured in nm
* @param epsilon the epsilon parameter of the Lennard-Jones potential (corresponding to the well depth of the van der Waals interaction), measured in kJ/mol
* @param[out] charge the charge of the particle, measured in units of the proton charge
* @param[out] sigma the sigma parameter of the Lennard-Jones potential (corresponding to the van der Waals radius of the particle), measured in nm
* @param[out] epsilon the epsilon parameter of the Lennard-Jones potential (corresponding to the well depth of the van der Waals interaction), measured in kJ/mol
* Get the force field parameters for an interaction that should be calculated differently from others.
*
* @param index the index of the interaction for which to get parameters
* @param particle1 the index of the first particle involved in the interaction
* @param particle2 the index of the second particle involved in the interaction
* @param chargeProd the scaled product of the atomic charges (i.e. the strength of the Coulomb interaction), measured in units of the proton charge squared
* @param sigma the sigma parameter of the Lennard-Jones potential (corresponding to the van der Waals radius of the particle), measured in nm
* @param epsilon the epsilon parameter of the Lennard-Jones potential (corresponding to the well depth of the van der Waals interaction), measured in kJ/mol
* @param[out] particle1 the index of the first particle involved in the interaction
* @param[out] particle2 the index of the second particle involved in the interaction
* @param[out] chargeProd the scaled product of the atomic charges (i.e. the strength of the Coulomb interaction), measured in units of the proton charge squared
* @param[out] sigma the sigma parameter of the Lennard-Jones potential (corresponding to the van der Waals radius of the particle), measured in nm
* @param[out] epsilon the epsilon parameter of the Lennard-Jones potential (corresponding to the well depth of the van der Waals interaction), measured in kJ/mol