1 // ******************************************************************************
2 //
3 // Title: Force Field X.
4 // Description: Force Field X - Software for Molecular Biophysics.
5 // Copyright: Copyright (c) Michael J. Schnieders 2001-2025.
6 //
7 // This file is part of Force Field X.
8 //
9 // Force Field X is free software; you can redistribute it and/or modify it
10 // under the terms of the GNU General Public License version 3 as published by
11 // the Free Software Foundation.
12 //
13 // Force Field X is distributed in the hope that it will be useful, but WITHOUT
14 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
15 // FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
16 // details.
17 //
18 // You should have received a copy of the GNU General Public License along with
19 // Force Field X; if not, write to the Free Software Foundation, Inc., 59 Temple
20 // Place, Suite 330, Boston, MA 02111-1307 USA
21 //
22 // Linking this library statically or dynamically with other modules is making a
23 // combined work based on this library. Thus, the terms and conditions of the
24 // GNU General Public License cover the whole combination.
25 //
26 // As a special exception, the copyright holders of this library give you
27 // permission to link this library with independent modules to produce an
28 // executable, regardless of the license terms of these independent modules, and
29 // to copy and distribute the resulting executable under terms of your choice,
30 // provided that you also meet, for each linked independent module, the terms
31 // and conditions of the license of that module. An independent module is a
32 // module which is not derived from or based on this library. If you modify this
33 // library, you may extend this exception to your version of the library, but
34 // you are not obligated to do so. If you do not wish to do so, delete this
35 // exception statement from your version.
36 //
37 // ******************************************************************************
38 package ffx.openmm.drude;
39
40 import static edu.uiowa.jopenmm.OpenMMDrudeLibrary.OpenMM_DrudeSCFIntegrator_create;
41 import static edu.uiowa.jopenmm.OpenMMDrudeLibrary.OpenMM_DrudeSCFIntegrator_destroy;
42 import static edu.uiowa.jopenmm.OpenMMDrudeLibrary.OpenMM_DrudeSCFIntegrator_getMinimizationErrorTolerance;
43 import static edu.uiowa.jopenmm.OpenMMDrudeLibrary.OpenMM_DrudeSCFIntegrator_setMinimizationErrorTolerance;
44 import static edu.uiowa.jopenmm.OpenMMDrudeLibrary.OpenMM_DrudeSCFIntegrator_step;
45
46 /**
47 * This is a leap-frog Verlet Integrator that simulates systems with Drude particles. It uses the
48 * self-consistent field (SCF) method: at every time step, the positions of Drude particles are
49 * adjusted to minimize the potential energy.
50 * <p>
51 * This Integrator requires the System to include a DrudeForce, which it uses to identify the Drude
52 * particles.
53 */
54 public class DrudeSCFIntegrator extends DrudeIntegrator {
55
56 /**
57 * Create a DrudeSCFIntegrator.
58 *
59 * @param stepSize the step size with which to integrator the system (in picoseconds)
60 */
61 public DrudeSCFIntegrator(double stepSize) {
62 super(OpenMM_DrudeSCFIntegrator_create(stepSize));
63 }
64
65 /**
66 * Destroy the integrator.
67 * <p>
68 * This method releases the memory associated with the DrudeSCFIntegrator object.
69 * After calling this method, the integrator should not be used.
70 */
71 @Override
72 public void destroy() {
73 if (pointer != null) {
74 OpenMM_DrudeSCFIntegrator_destroy(pointer);
75 pointer = null;
76 }
77 }
78
79 /**
80 * Get the error tolerance to use when minimizing the potential energy. This roughly corresponds
81 * to the maximum allowed force magnitude on the Drude particles after minimization.
82 *
83 * @return the error tolerance to use, measured in kJ/mol/nm
84 */
85 public double getMinimizationErrorTolerance() {
86 return OpenMM_DrudeSCFIntegrator_getMinimizationErrorTolerance(pointer);
87 }
88
89 /**
90 * Set the error tolerance to use when minimizing the potential energy. This roughly corresponds
91 * to the maximum allowed force magnitude on the Drude particles after minimization.
92 *
93 * @param tolerance the error tolerance to use, measured in kJ/mol/nm
94 */
95 public void setMinimizationErrorTolerance(double tolerance) {
96 OpenMM_DrudeSCFIntegrator_setMinimizationErrorTolerance(pointer, tolerance);
97 }
98
99 /**
100 * Advance a simulation through time by taking a series of time steps.
101 *
102 * @param steps the number of time steps to take
103 */
104 @Override
105 public void step(int steps) {
106 OpenMM_DrudeSCFIntegrator_step(pointer, steps);
107 }
108 }