bonded_interaction_data.hpp

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/*
 * Copyright (C) 2010-2026 The ESPResSo project
 *
 * This file is part of ESPResSo.
 *
 * ESPResSo is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * ESPResSo is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#pragma once
 
/** @file
 *  Data structures for bonded interactions.
 *  For more information on how to add new interactions, see @ref bondedIA_new.
 */
 
#include <config/config.hpp>
 
#include "angle_cosine.hpp"
#include "angle_cossquare.hpp"
#include "angle_harmonic.hpp"
#include "bonded_coulomb.hpp"
#include "bonded_coulomb_sr.hpp"
#include "bonded_tab.hpp"
#include "dihedral.hpp"
#include "fene.hpp"
#include "harmonic.hpp"
#include "immersed_boundary/ibm_tribend.hpp"
#include "immersed_boundary/ibm_triel.hpp"
#include "immersed_boundary/ibm_volcons.hpp"
#include "object-in-fluid/oif_global_forces_params.hpp"
#include "object-in-fluid/oif_local_forces.hpp"
#include "quartic.hpp"
#include "rigid_bond.hpp"
#include "thermalized_bond.hpp"
 
#include "BondList.hpp"
#include "Particle.hpp"
#include "system/Leaf.hpp"
 
#include <algorithm>
#include <cassert>
#include <cmath>
#include <memory>
#include <optional>
#include <unordered_map>
#include <variant>
 
/** Interaction type for unused bonded interaction slots */
struct NoneBond {
  static constexpr int num = 0;
  double cutoff() const { return bonded_inactive_cutoff; }
};
 
/** Interaction type for virtual bonds */
struct VirtualBond {
  static constexpr int num = 1;
  double cutoff() const { return bonded_inactive_cutoff; }
};
 
/** Variant in which to store the parameters of an individual bonded
 *  interaction
 */
using Bonded_IA_Parameters =
    std::variant<NoneBond, FeneBond, HarmonicBond, QuarticBond, BondedCoulomb,
                 BondedCoulombSR, AngleHarmonicBond, AngleCosineBond,
                 AngleCossquareBond, DihedralBond, TabulatedDistanceBond,
                 TabulatedAngleBond, TabulatedDihedralBond, ThermalizedBond,
                 RigidBond, IBMTriel, IBMVolCons, IBMTribend,
                 OifGlobalForcesBond, OifLocalForcesBond, VirtualBond>;
 
/**
 * @brief container for bonded interactions.
 */
class BondedInteractionsMap : public System::Leaf<BondedInteractionsMap> {
  using container_type =
      std::unordered_map<int, std::shared_ptr<Bonded_IA_Parameters>>;
 
public:
  using key_type = container_type::key_type;
  using mapped_type = container_type::mapped_type;
  using value_type = container_type::value_type;
  using iterator = container_type::iterator;
  using const_iterator = container_type::const_iterator;
 
  BondedInteractionsMap() = default;
  virtual ~BondedInteractionsMap() = default;
 
  iterator begin() { return m_params.begin(); }
  iterator end() { return m_params.end(); }
  const_iterator begin() const { return m_params.begin(); }
  const_iterator end() const { return m_params.end(); }
 
  void insert(key_type const &key, mapped_type const &ptr) {
    if (m_params.contains(key)) {
      deactivate_bond(m_params.at(key));
    }
    activate_bond(ptr);
    next_key = std::max(next_key, key + 1);
    m_params[key] = ptr;
    on_ia_change();
  }
  key_type insert(mapped_type const &ptr) {
    activate_bond(ptr);
    auto const key = next_key++;
    m_params[key] = ptr;
    on_ia_change();
    return key;
  }
  auto erase(key_type const &key) {
    if (m_params.contains(key)) {
      deactivate_bond(m_params.at(key));
    }
    auto &&obj = m_params.erase(key);
    on_ia_change();
    return obj;
  }
  virtual void activate_bond(mapped_type const &ptr);
  virtual void deactivate_bond(mapped_type const &ptr);
  mapped_type const &at(key_type const &key) const { return m_params.at(key); }
  bool contains(key_type const &key) const { return m_params.contains(key); }
  bool empty() const { return m_params.empty(); }
  auto size() const { return m_params.size(); }
  auto get_next_key() const { return next_key; }
  auto get_zero_based_type(int bond_id) const {
    return contains(bond_id) ? static_cast<int>(at(bond_id)->index()) : 0;
  }
  auto get_n_thermalized_bonds() const {
    assert(n_thermalized_bonds >= 0);
    return n_thermalized_bonds;
  }
#ifdef ESPRESSO_BOND_CONSTRAINT
  auto get_n_rigid_bonds() const {
    assert(n_rigid_bonds >= 0);
    return n_rigid_bonds;
  }
#endif
  std::optional<key_type> find_bond_id(mapped_type const &target_bond) const {
    for (auto const &[bond_id, bond] : m_params) {
      if (bond == target_bond) {
        return bond_id;
      }
    }
    return std::nullopt;
  }
 
  /**
   * @brief Calculate the maximal cutoff of bonded interactions, required to
   * determine the cell size for communication.
   *
   * Bond angle and dihedral potentials do not contain a cutoff intrinsically.
   * The cutoff for these potentials depends on the bond length potentials
   * (it is assumed that particles participating in a bond angle or dihedral
   * potential are bound to each other by some bond length potential). For bond
   * angle potentials nothing has to be done. For dihedral potentials the cutoff
   * is set to twice the maximal cutoff because the particle in which the bond
   * is stored is only bonded to the first two partners, one of which has an
   * additional bond to the third partner.
   */
  double maximal_cutoff() const;
 
  /**
   * @brief Checks both particles for a specific bond, even on ghost particles.
   *
   * @param p           particle to check for the bond
   * @param p_partner   possible bond partner
   * @tparam BondType   Bond type to check for. Must be of one of the types in
   *                    @ref Bonded_IA_Parameters.
   */
  template <typename BondType>
  bool pair_bond_exists_on(Particle const &p, Particle const &p_partner) const {
    auto const &bonds = p.bonds();
    return std::any_of(
        bonds.begin(), bonds.end(),
        [this, partner_id = p_partner.id()](BondView const &bond) {
          auto const &bond_ptr = at(bond.bond_id());
          return std::holds_alternative<BondType>(*bond_ptr.get()) and
                 (bond.partner_ids()[0] == partner_id);
        });
  }
 
  /**
   * @brief Checks both particles for a specific bond, even on ghost particles.
   *
   * @param p1     particle on which the bond may be stored
   * @param p2     particle on which the bond may be stored
   * @tparam BondType Bond type to check for.
   */
  template <typename BondType>
  bool pair_bond_exists_between(Particle const &p1, Particle const &p2) const {
    if (&p1 == &p2)
      return false;
 
    // Check if particles have bonds and search for the bond of interest.
    // Could be saved on either particle, so we need to check both.
    return pair_bond_exists_on<BondType>(p1, p2) or
           pair_bond_exists_on<BondType>(p2, p1);
  }
 
  void on_ia_change();
 
private:
  container_type m_params = {};
  key_type next_key = static_cast<key_type>(0);
  int n_thermalized_bonds = 0;
#ifdef ESPRESSO_BOND_CONSTRAINT
  int n_rigid_bonds = 0;
#endif
};
 
/** @brief Get the number of bonded partners for the specified bond. */
inline int number_of_partners(Bonded_IA_Parameters const &iaparams) {
  return std::visit([]<typename T>(T const &) { return T::num; }, iaparams);
}