LennardJonesForce.cpp

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#include "LennardJonesForce.h"
 
#include "utils/ArrayUtils.h"
 
std::array<double, 3UL> LennardJonesForce::calculateForce(const Particle& p, const Particle& q) const {
    const auto displacement = q.getX() - p.getX();
    const double distSq = ArrayUtils::L2NormSquared(displacement);
 
    const double sigma = (p.getSigma() + q.getSigma()) / 2;
    const double epsilon = std::sqrt(p.getEpsilon() * q.getEpsilon());
 
    const double sigma_dist_pow_6 = std::pow(sigma * sigma / distSq, 3);
 
    const auto f_lennard_jones = (24 * epsilon / distSq) * (sigma_dist_pow_6 * (1 - 2 * sigma_dist_pow_6)) * displacement;
 
    return f_lennard_jones;
};
 
LennardJonesForce::operator std::string() const { return "Lennard-Jones"; };