SocketNWChemPot.h

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/*
** This file is part of eOn.
**
** SPDX-License-Identifier: BSD-3-Clause
**
** Copyright (c) 2010--present, eOn Development Team
** All rights reserved.
**
** Repo:
** https://github.com/TheochemUI/eOn
*/
#pragma once
 
#include "eon/Potential.h"
#include <memory>
#include <string>

class SocketNWChemPot : public eonc::Potential {
public:
  explicit SocketNWChemPot(const eonc::Parameters &p);
  ~SocketNWChemPot() override;

  void write_nwchem_template(const std::string &filename, long N,
                             const std::vector<std::string> &atom_symbols);

  void force(long N, const double *R, const int *atomicNrs, double *F,
             double *U, double *variance, const double *box) override;

  [[nodiscard]] bool requiresIsolatedMoleculeLayout() const noexcept override {
    return true;
  }
  [[nodiscard]] bool isThreadSafe() const noexcept override { return false; }
  [[nodiscard]] bool needsPerImageInstance() const noexcept override {
    return false;
  }
 
  [[nodiscard]] bool computesStress() const noexcept override {
    return haveStress_;
  }
 
  [[nodiscard]] Matrix3d cauchyStress() const override { return stress_; }
 
private:
  // --- Private Methods ---
  void setup_server();
  void accept_connection();
  void drop_connection();
  void forceOnce(long N, const double *R, const int *atomicNrs, double *F,
                 double *U, double *variance, const double *box);
  void send_header(const char *msg);
  void recv_header(char *buffer);
  void send_exact(const void *buffer, size_t n_bytes);
  void recv_exact(void *buffer, size_t n_bytes);
 
  // --- Member Variables ---
  // Socket configuration
  bool unix_socket_mode;
  // For TCP, the host; for UNIX, the full socket path.
  std::string server_address;
  // The original name for the .nwi file.
  std::string unix_socket_basename;
  // File containing actual calculation parameters
  std::string nwchem_settings;
  int port, mem_in_gb;
  // Generate a template input
  bool make_template_input;
 
  // Socket state
  int listen_fd{-1};
  int conn_fd{-1};
  bool is_connected{false};
 
  // --- Constants for i-PI protocol and unit conversions ---
  static constexpr int MSG_LEN = 12;
  // From ASE units, values for eV and Angstrom
  static constexpr double BOHR_IN_ANGSTROM = 0.529177210903;
  static constexpr double HARTREE_IN_EV = 27.211386245988;
 
  Matrix3d stress_{Matrix3d::Zero()};
  bool haveStress_{false};
};