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G4DNASmoluchowskiReactionModel.cc
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28 #include "Randomize.hh"
29 #include "G4Track.hh"
31 #include "G4UnitsTable.hh"
32 #include "G4Molecule.hh"
33 #include "G4Exp.hh"
34 
37  , fpReactionData(nullptr)
38 {
39 }
40 
42 
44  const G4Track&)
45 {
47 }
48 
50 {
52 }
53 
55  const G4MolecularConfiguration* pMol2)
56 {
58  return __output;
59 }
60 
62 {
63  G4double __output = (*fpReactionData)[__i]->GetEffectiveReactionRadius();
64  return __output;
65 }
66 
68  const G4Track& __trackB,
69  const G4double __reactionRadius,
70  G4double& __separationDistance,
71  const G4bool __alongStepReaction)
72 {
73  const G4double R2 = __reactionRadius * __reactionRadius;
74  G4double postStepSeparation = 0.;
75  bool do_break = false;
76  int k = 0;
77 
78  for (; k < 3; ++k)
79  {
80  postStepSeparation += std::pow(
81  __trackA.GetPosition()[k] - __trackB.GetPosition()[k], 2);
82 
83  if (postStepSeparation > R2)
84  {
85  do_break = true;
86  break;
87  }
88  }
89 
90  if (do_break == false)
91  {
92  // The loop was not break
93  // => r^2 < R^2
94  __separationDistance = std::sqrt(postStepSeparation);
95  return true;
96  }
97  else if (__alongStepReaction == true)
98  {
99  //Along step check and the loop has break
100 
101  // Continue loop
102  for (; k < 3; ++k)
103  {
104  postStepSeparation += std::pow(
105  __trackA.GetPosition()[k] - __trackB.GetPosition()[k], 2);
106  }
107  // Use Green approach : the Brownian bridge
108  __separationDistance = (postStepSeparation = std::sqrt(postStepSeparation));
109 
110  auto pMoleculeA = GetMolecule(__trackA);
111  auto pMoleculeB = GetMolecule(__trackB);
112 
113  G4double D = pMoleculeA->GetDiffusionCoefficient()
114  + pMoleculeB->GetDiffusionCoefficient();
115 
116  const auto& preStepPositionA = __trackA.GetStep()->GetPreStepPoint()->GetPosition();
117  const auto& preStepPositionB = __trackB.GetStep()->GetPreStepPoint()->GetPosition();
118 
119  G4double preStepSeparation = (preStepPositionA - preStepPositionB).mag();
120 
121  //===================================
122  // Brownian bridge
123  G4double __probabiltyOfEncounter = G4Exp(-(preStepSeparation - __reactionRadius)
124  * (postStepSeparation - __reactionRadius)
125  / (D * (__trackB.GetStep()->GetDeltaTime()))
126  );
127  G4double __selectedPOE = G4UniformRand();
128 
129  if (__selectedPOE <= __probabiltyOfEncounter)
130  {
131  return true;
132  }
133  //===================================
134  }
135 
136  return false;
137 }