ObjectiveFunction.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 "Matter.h"
 
#include <optional>
 
namespace eonc {
 
class ObjectiveFunction {
protected:
  const Parameters &params;
 
public:
  ObjectiveFunction(const Parameters &paramsPassed) : params{paramsPassed} {}
  virtual ~ObjectiveFunction() {}
  virtual double getEnergy() = 0;
  virtual VectorXd getGradient(bool fdstep = false) = 0;
  virtual void setPositions(const VectorXd &x) = 0;
  virtual VectorXd getPositions() = 0;
  virtual int degreesOfFreedom() = 0;
  virtual bool isConverged() = 0;
  virtual double getConvergence() = 0;
  virtual VectorXd difference(const VectorXd &a, const VectorXd &b) = 0;
  // Allow the initial finite-difference curvature estimate used by L-BFGS.
  virtual bool supportsFiniteDifferenceCurvature() const { return true; }
  // A curvature the objective already knows (eV / A^2, magnitude), so
  // L-BFGS can seed H0 from it instead of spending a force call on the
  // finite-difference probe. Empty when nothing is known.
  virtual std::optional<double> knownCurvature() const { return std::nullopt; }
  // Packwood/Kermode pair preconditioner: MIC of one Cartesian pair.
  // Default leaves dr unchanged (no cell).
  virtual void minimumImage(Eigen::Ref<Eigen::Vector3d> /*dr*/) const {}
  // Per-atom masses of the free atoms (length N, not 3N). Empty if unknown.
  virtual VectorXd getMasses() const { return VectorXd(); }
  // True when the geometry uses periodic boundaries (Sella proj_rot off).
  virtual bool getPeriodic() const { return false; }
};
 
} // namespace eonc