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
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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
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35 // exception statement from your version.
36 //
37 // ******************************************************************************
38 package ffx.numerics.multipole;
39
40 import jdk.incubator.vector.DoubleVector;
41
42 import static ffx.numerics.multipole.TholeTensorGlobalSIMD.tholeSource;
43
44 /**
45 * The TholeTensorQI class computes derivatives of Thole damping via recursion to order <= 4 for
46 * Cartesian multipoles in a quasi-internal frame.
47 *
48 * @author Michael J. Schnieders
49 * @see <a href="http://doi.org/10.1142/9789812830364_0002" target="_blank"> Matt Challacombe, Eric
50 * Schwegler and Jan Almlof, Modern developments in Hartree-Fock theory: Fast methods for
51 * computing the Coulomb matrix. Computational Chemistry: Review of Current Trends. pp. 53-107,
52 * Ed. J. Leczszynski, World Scientifc, 1996. </a>
53 * @since 1.0
54 */
55 public class TholeTensorQISIMD extends CoulombTensorQISIMD {
56
57 /**
58 * Thole damping parameter is set to min(pti,ptk)).
59 */
60 private DoubleVector thole;
61
62 /**
63 * AiAk parameter = 1/(alphaI^6*alphaK^6) where alpha is polarizability.
64 */
65 private DoubleVector AiAk;
66
67 /**
68 * Constructor for TholeTensorQI.
69 *
70 * @param order Tensor order.
71 * @param thole Thole damping parameter is set to min(pti,ptk)).
72 * @param AiAk parameter = 1/(alphaI^6*alphaK^6) where alpha is polarizability.
73 */
74 public TholeTensorQISIMD(int order, DoubleVector thole, DoubleVector AiAk) {
75 super(order);
76 this.thole = thole;
77 this.AiAk = AiAk;
78 this.operator = Operator.THOLE_FIELD;
79
80 // Source terms are currently defined up to order 4.
81 assert (order <= 4);
82 }
83
84 /**
85 * Set Thole damping parameters
86 *
87 * @param thole a double.
88 * @param AiAk a double.
89 */
90 public void setThole(DoubleVector thole, DoubleVector AiAk) {
91 this.thole = thole;
92 this.AiAk = AiAk;
93 }
94
95 /**
96 * Check if the Thole damping is exponential is greater than zero (or the interaction can be
97 * neglected).
98 *
99 * @param r The separation distance.
100 * @return True if -thole*u^3 is greater than -50.0.
101 */
102 public boolean checkThole(DoubleVector r) {
103 return TholeTensorGlobalSIMD.checkThole(thole, AiAk, r);
104 }
105
106 /**
107 * Generate source terms for the Challacombe et al. recursion.
108 *
109 * @param T000 Location to store the source terms.
110 */
111 protected void source(DoubleVector[] T000) {
112 // Compute the normal Coulomb auxiliary term.
113 super.source(T000);
114
115 // Add the Thole damping terms: edamp = exp(-thole*u^3).
116 tholeSource(thole, AiAk, R, T000);
117 }
118
119 }