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// This is the forcefield file for the Dipolar Unified-atom Force Field (DUFF) |
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// |
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// The sections are divided into AtomTypes |
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// |
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// many parameters (but not all) are derived from the TRAPPE force field |
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// of Siepmann's group. |
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|
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begin BaseAtomTypes |
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//Name mass (amu) |
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O 15.9994 |
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H 1.0079 |
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M 0.0 |
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end BaseAtomTypes |
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|
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begin AtomTypes |
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//Name mass (amu) |
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O_TIP4P_FQ O |
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H_TIP4P_FQ H |
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M_TIP4P_FQ M |
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end AtomTypes |
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|
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begin LennardJonesAtomTypes |
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//Name epsilon sigma |
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O_TIP4P_FQ 0.2862 3.159 |
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end LennardJonesAtomTypes |
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|
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begin ChargeAtomTypes |
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// Name charge |
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//O_TIP4P_FQ 0.0 |
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//H_TIP4P_FQ 0.0 |
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//M_TIP4P_FQ 0.0 |
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end ChargeAtomTypes |
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|
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|
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begin FluctuatingChargeAtomTypes |
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//Values obtained from Rick, Stuart, and Berne J Chem Phys, 1994, 101 |
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//Since they gave chi as an electronegativity difference, we will assign Oxygen's (the M site |
| 38 |
//actually for TIP4P) electronegativity from Rappe and Goddard III, and setting H to equal |
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//the difference |
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// Rappe and Goddard, O or M chi: 8.741 eV = 201.5705 kcal/mol |
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// Rick, Stuart, and Berne, delta Chi between O and H = 68.49 |
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// SlaterZeta has units of Bohr radius |
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// Fictitious ChargeMass has units of (fs / e)^2 kcal / mol (note the ps->fs difference between |
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// this code and the Rick, Stuart, and Berne paper |
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//Name ChargeMass (fs^2 kcal/e^2 mol) chi (kcal/mol e) hardness (kcal/(mol*e^2)) slaterN slaterZeta |
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H_TIP4P_FQ 60.0 Hardness 133.0805 353.0 1 0.90 |
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M_TIP4P_FQ 60.0 Hardness 201.5705 371.6 2 1.63 |
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end FluctuatingChargeAtomTypes |
