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1   // ******************************************************************************
2   //
3   // Title:       Force Field X.
4   // Description: Force Field X - Software for Molecular Biophysics.
5   // Copyright:   Copyright (c) Michael J. Schnieders 2001-2021.
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.parameters;
39  
40  import static ffx.potential.parameters.ForceField.ForceFieldType.CHARGE;
41  import static ffx.utilities.KeywordGroup.PotentialFunctionParameter;
42  import static java.lang.Integer.parseInt;
43  import static java.lang.String.format;
44  
45  import ffx.utilities.FFXKeyword;
46  import java.util.Comparator;
47  
48  /**
49   * The ChargeType class defines a partial atomic charge type.
50   *
51   * @author Michael J. Schnieders
52   * @since 1.0
53   */
54  @FFXKeyword(name = "charge", clazz = String.class, keywordGroup = PotentialFunctionParameter,
55      description = "[1 integer and 1 real] "
56          + "Provides a value for a single atomic partial charge electrostatic parameter. "
57          + "The integer modifier, if positive, gives the atom type number for which the charge parameter is to be defined. "
58          + "Note that charge parameters are given for atom types, not atom classes. "
59          + "If the integer modifier is negative, then the parameter value to follow applies only to the individual atom whose atom number is the negative of the modifier. "
60          + "The real number modifier gives the values of the atomic partial charge in electrons.")
61  public final class ChargeType extends BaseType implements Comparator<String> {
62  
63    /** Partial atomic charge in units of electrons. */
64    public final double charge;
65    /** The atom type that uses this charge parameter. */
66    public int atomType;
67  
68    /**
69     * ChargeType constructor.
70     *
71     * @param atomType int
72     * @param charge double
73     */
74    public ChargeType(int atomType, double charge) {
75      super(CHARGE, "" + atomType);
76      this.atomType = atomType;
77      this.charge = charge;
78    }
79  
80    /**
81     * Average two ChargeType instances. The atom type that defines the new type must be supplied.
82     *
83     * @param chargeType1 a {@link ffx.potential.parameters.ChargeType} object.
84     * @param chargeType2 a {@link ffx.potential.parameters.ChargeType} object.
85     * @param atomType a int.
86     * @return a {@link ffx.potential.parameters.ChargeType} object.
87     */
88    public static ChargeType average(ChargeType chargeType1, ChargeType chargeType2, int atomType) {
89      if (chargeType1 == null || chargeType2 == null) {
90        return null;
91      }
92      double charge = (chargeType1.charge + chargeType2.charge) / 2.0;
93      return new ChargeType(atomType, charge);
94    }
95  
96    /** {@inheritDoc} */
97    @Override
98    public int compare(String s1, String s2) {
99      int t1 = parseInt(s1);
100     int t2 = parseInt(s2);
101     return Integer.compare(t1, t2);
102   }
103 
104   /**
105    * incrementType
106    *
107    * @param increment a int.
108    */
109   public void incrementType(int increment) {
110     this.atomType += increment;
111   }
112 
113   /**
114    * {@inheritDoc}
115    *
116    * <p>Nicely formatted Charge type.
117    */
118   @Override
119   public String toString() {
120     return format("charge  %5d  % 7.5f", atomType, charge);
121   }
122 }