saftvrmie.hpp

/***
 
 \brief This file contains the contributions that can be composed together to form SAFT models

*/

#pragma once

#include "nlohmann/json.hpp"
#include "teqp/types.hpp"
#include "teqp/json_tools.hpp"
#include "teqp/exceptions.hpp"
#include "teqp/constants.hpp"
#include "teqp/math/quadrature.hpp"
#include "teqp/models/saft/polar_terms.hpp"
#include <optional>
#include <variant>

namespace teqp {
namespace SAFTVRMie {

/// Coefficients for one fluid
struct SAFTVRMieCoeffs {
    std::string name; ///< Name of fluid
    double m = -1, ///< number of segments
        sigma_m = -1, ///< [m] segment diameter
        epsilon_over_k = -1, ///< [K] depth of pair potential divided by Boltzman constant
        lambda_a = -1, ///< The attractive exponent (the 6 in LJ 12-6 potential)
        lambda_r = -1, ///< The repulsive exponent (the 12 in LJ 12-6 potential)
        mustar2 = 0, ///< nondimensional, the reduced dipole moment squared
        nmu = 0, ///< number of dipolar segments
        Qstar2 = 0, ///< nondimensional, the reduced quadrupole squared
        nQ = 0; ///< number of quadrupolar segments
    std::string BibTeXKey; ///< The BibTeXKey for the reference for these coefficients
};

/// Manager class for SAFT-VR-Mie coefficients
class SAFTVRMieLibrary {
    std::map<std::string, SAFTVRMieCoeffs> coeffs;
public:
    SAFTVRMieLibrary() {
        insert_normal_fluid("Methane", 1.0000, 3.7412e-10, 153.36, 12.650, 6, "Lafitte-JCP-2001");
        insert_normal_fluid("Ethane", 1.4373, 3.7257e-10, 206.12, 12.400, 6, "Lafitte-JCP-2001");
        insert_normal_fluid("Propane", 1.6845, 3.9056e-10, 239.89, 13.006, 6, "Lafitte-JCP-2001");
    }
    void insert_normal_fluid(const std::string& name, double m, const double sigma_m, const double epsilon_over_k, const double lambda_r, const double lambda_a, const std::string& BibTeXKey) {
        SAFTVRMieCoeffs coeff;
        coeff.name = name;
        coeff.m = m;
        coeff.sigma_m = sigma_m;
        coeff.epsilon_over_k = epsilon_over_k;
        coeff.lambda_r = lambda_r;
        coeff.lambda_a = lambda_a;
        coeff.BibTeXKey = BibTeXKey;
        coeffs.insert(std::pair<std::string, SAFTVRMieCoeffs>(name, coeff));
    }
    const auto& get_normal_fluid(const std::string& name) {
        auto it = coeffs.find(name);
        if (it != coeffs.end()) {
            return it->second;
        }
        else {
            throw std::invalid_argument("Bad name:" + name);
        }
    }
    auto get_coeffs(const std::vector<std::string>& names){
        std::vector<SAFTVRMieCoeffs> c;
        for (auto n : names){
            c.push_back(get_normal_fluid(n));
        }