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.potential.nonbonded;
39
40 /**
41 * This class contains fields and methods for maintaining details of non-bonded cutoffs.
42 *
43 * @author Michael J. Schnieders
44 */
45 public class NonbondedCutoff {
46
47 /** At the distance "cut", a multiplicative switch begins to be applied. */
48 public final double cut;
49 /** The distance cut squared. */
50 public final double cut2;
51 /** All vdW interactions are 0 at the distance "off". */
52 public final double off;
53 /** The distance off squared. */
54 public final double off2;
55 /**
56 * A buffer added to the cut-off distance <code>off</code> to define neighbors included when
57 * collecting Verlet lists.
58 */
59 public final double buff;
60 /**
61 * Non-bonded Cutoff constructor.
62 *
63 * @param off All vdW interactions are 0 at the distance <code>off</code>.
64 * @param cut At the distance <code>cut</code>, a multiplicative switch begins to be applied.
65 * @param buff A buffer added to the cut-off distance <code>off</code> to define neighbors
66 * included when collecting Verlet lists.
67 */
68 public NonbondedCutoff(double off, double cut, double buff) {
69 this.cut = cut;
70 this.cut2 = cut * cut;
71 this.off = off;
72 this.off2 = off * off;
73 this.buff = buff;
74 }
75
76 /**
77 * Returns a NonbondedCutoff that does not cut off anything.
78 *
79 * @return No-cutoff cutoff.
80 */
81 public static NonbondedCutoff noCutoffFactory() {
82 return new NonbondedCutoff(Double.MAX_VALUE, Double.MAX_VALUE, 0.0);
83 }
84 }