79 lines
2.0 KiB
ReStructuredText
79 lines
2.0 KiB
ReStructuredText
TIP3P water model
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=================
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The TIP3P water model as implemented in CHARMM
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:ref:`(MacKerell) <howto-tip3p>` specifies a 3-site rigid water molecule with
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charges and Lennard-Jones parameters assigned to each of the 3 atoms.
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In LAMMPS the :doc:`fix shake <fix_shake>` command can be used to hold
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the two O-H bonds and the H-O-H angle rigid. A bond style of
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*harmonic* and an angle style of *harmonic* or *charmm* should also be
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used.
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These are the additional parameters (in real units) to set for O and H
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atoms and the water molecule to run a rigid TIP3P-CHARMM model with a
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cutoff. The K values can be used if a flexible TIP3P model (without
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fix shake) is desired. If the LJ epsilon and sigma for HH and OH are
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set to 0.0, it corresponds to the original 1983 TIP3P model
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:ref:`(Jorgensen) <Jorgensen1>`.
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| O mass = 15.9994
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| H mass = 1.008
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| O charge = -0.834
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| H charge = 0.417
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| LJ epsilon of OO = 0.1521
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| LJ sigma of OO = 3.1507
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| LJ epsilon of HH = 0.0460
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| LJ sigma of HH = 0.4000
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| LJ epsilon of OH = 0.0836
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| LJ sigma of OH = 1.7753
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| K of OH bond = 450
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| r0 of OH bond = 0.9572
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| K of HOH angle = 55
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| theta of HOH angle = 104.52
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These are the parameters to use for TIP3P with a long-range Coulombic
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solver (e.g. Ewald or PPPM in LAMMPS), see :ref:`(Price) <Price1>` for
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details:
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| O mass = 15.9994
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| H mass = 1.008
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| O charge = -0.830
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| H charge = 0.415
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| LJ epsilon of OO = 0.102
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| LJ sigma of OO = 3.188
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| LJ epsilon, sigma of OH, HH = 0.0
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| K of OH bond = 450
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| r0 of OH bond = 0.9572
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| K of HOH angle = 55
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| theta of HOH angle = 104.52
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Wikipedia also has a nice article on `water models <http://en.wikipedia.org/wiki/Water_model>`_.
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----------
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.. _howto-tip3p:
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**(MacKerell)** MacKerell, Bashford, Bellott, Dunbrack, Evanseck, Field,
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Fischer, Gao, Guo, Ha, et al, J Phys Chem, 102, 3586 (1998).
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.. _Jorgensen1:
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**(Jorgensen)** Jorgensen, Chandrasekhar, Madura, Impey, Klein, J Chem
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Phys, 79, 926 (1983).
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.. _Price1:
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**(Price)** Price and Brooks, J Chem Phys, 121, 10096 (2004).
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