MPQC  2.3.1
tbgrad.h
1 //
2 // tbgrad.h --- definition of the abstract two-electron gradient builder
3 //
4 // Copyright (C) 1996 Limit Point Systems, Inc.
5 //
6 // Author: Edward Seidl <seidl@janed.com>
7 // Maintainer: LPS
8 //
9 // This file is part of the SC Toolkit.
10 //
11 // The SC Toolkit is free software; you can redistribute it and/or modify
12 // it under the terms of the GNU Library General Public License as published by
13 // the Free Software Foundation; either version 2, or (at your option)
14 // any later version.
15 //
16 // The SC Toolkit is distributed in the hope that it will be useful,
17 // but WITHOUT ANY WARRANTY; without even the implied warranty of
18 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 // GNU Library General Public License for more details.
20 //
21 // You should have received a copy of the GNU Library General Public License
22 // along with the SC Toolkit; see the file COPYING.LIB. If not, write to
23 // the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
24 //
25 // The U.S. Government is granted a limited license as per AL 91-7.
26 //
27 
28 #ifndef _chemistry_qc_scf_tbgrad_h
29 #define _chemistry_qc_scf_tbgrad_h
30 
31 #ifdef __GNUC__
32 #pragma interface
33 #endif
34 
35 #include <util/group/thread.h>
36 
37 namespace sc {
38 
39 template<class T>
40 class TBGrad : public Thread {
41  protected:
42  T& contribution;
43  double exchange_fraction;
44 
45  public:
46  TBGrad(T&t, double ex = 1.0) : contribution(t), exchange_fraction(ex) {}
47  virtual ~TBGrad() {}
48 
49  inline void set_scale(double& coulombscale, double& exchangescale,
50  int i, int j, int k, int l) const
51  {
52  double scale = 1.0;
53 
54  if ((i!=k)||(j!=l))
55  scale *= 2.0;
56 
57  if (i!=j)
58  scale *= 2.0;
59 
60  coulombscale = 0.5*scale;
61  exchangescale = -0.25*scale * exchange_fraction;
62 
63  if (k!=l)
64  coulombscale *= 2.0;
65 
66  if ((k!=l)&&(i==j))
67  exchangescale *= 2.0;
68  }
69 };
70 
71 }
72 
73 #endif
74 
75 // Local Variables:
76 // mode: c++
77 // c-file-style: "ETS"
78 // End:
sc::Thread
The Thread abstract class defines an interface which must be implemented by classes wishing to be run...
Definition: thread.h:79
sc::TBGrad
Definition: tbgrad.h:40
sc::contribution
Definition: petite.h:74

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