SteepestDescent.cpp

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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
*/
 
// Based on the SteepestDescent minimizer written in ASE.
 
#include "eon/SteepestDescent.h"
#include "eon/SafeMath.h"
 
namespace eonc {
 
int SteepestDescent::step(double a_maxMove) {
  Eigen::VectorXd r = m_objf->getPositions();
  Eigen::VectorXd f = -m_objf->getGradient();
 
  Eigen::VectorXd dr;
  double alpha = m_optConfig.opts.sd.alpha;
  if (m_optConfig.opts.sd.two_point && iteration > 0) {
    Eigen::VectorXd dx = m_objf->difference(r, m_rPrev);
    Eigen::VectorXd dg = -f + m_fPrev;
    alpha = eonc::safemath::safe_div(dx.dot(dx), dx.dot(dg), 0.0);
    if (alpha < 0) {
      alpha = m_optConfig.opts.sd.alpha;
    }
    QUILL_LOG_DEBUG(m_log, "[SD] alpha: {:.4e}", alpha);
  }
 
  dr = alpha * f;
  dr = eonc::geometry::maxAtomMotionAppliedV(dr, a_maxMove);
 
  m_objf->setPositions(r + dr);
 
  m_rPrev = r;
  m_fPrev = f;
 
  iteration++;
 
  return m_objf->isConverged() ? 1 : 0;
}
 
int SteepestDescent::run(size_t a_maxIteration, double a_maxMove) {
  while (!m_objf->isConverged() && iteration < a_maxIteration) {
    step(a_maxMove);
  }
  return m_objf->isConverged() ? 1 : 0;
}
 
} // namespace eonc