3
# The "gaff.lt" file is usually located in $MOLTEMPLATE_PATH (and is
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# distributed with moltemplate. See the "Installation" section in the manual.)
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# It contains definitions of the atoms "c3", "h1", as well as the bonded
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# and non-bonded interactions between them (and many other atoms).
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# Moltemplate is only a simple text manipulation tool. It cannot
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# calculate atomic charge using quantom chemistry methods.
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# Atom charges for this example were taken from the OPLSAA force field file:
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# http://dasher.wustl.edu/tinker/distribution/params/oplsaa.prm
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# However, normally simulations in AMBER are assigned charges using the
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# "HF/6-31G* RESP2" or "AM1-BCC3" methods using AmberTools.
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Isobutane inherits GAFF {
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# atomID molID atomTyle charge X Y Z
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$atom:C0 $mol:. @atom:c3 -0.0600 -0.001 -0.001 -0.439
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$atom:C1 $mol:. @atom:c3 -0.1800 -1.257 -0.726 0.078
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$atom:C2 $mol:. @atom:c3 -0.1800 1.258 -0.726 0.072
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$atom:C3 $mol:. @atom:c3 -0.1800 -0.001 1.453 0.069
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$atom:H0 $mol:. @atom:h1 0.0600 -0.003 -0.004 -1.439
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$atom:H11 $mol:. @atom:h1 0.0600 -2.075 -0.255 -0.254
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$atom:H12 $mol:. @atom:h1 0.0600 -1.256 -0.724 1.078
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$atom:H13 $mol:. @atom:h1 0.0600 -1.259 -1.669 -0.253
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$atom:H21 $mol:. @atom:h1 0.0600 2.074 -0.255 -0.264
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$atom:H22 $mol:. @atom:h1 0.0600 1.258 -1.669 -0.259
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$atom:H23 $mol:. @atom:h1 0.0600 1.261 -0.724 1.072
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$atom:H31 $mol:. @atom:h1 0.0600 -0.817 1.923 -0.263
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$atom:H32 $mol:. @atom:h1 0.0600 0.816 1.923 -0.268
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$atom:H33 $mol:. @atom:h1 0.0600 0.003 1.456 1.070
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# The "." in "$mol:." refers to this molecule object's molecule ID
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# (It means we do not expect this molecule to be a group or a subunit
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# of a larger molecule. Otherwise we would use "$mol:..." instead.)
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write('Data Bond List') {
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$bond:C01 $atom:C0 $atom:C1
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$bond:C02 $atom:C0 $atom:C2
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$bond:C03 $atom:C0 $atom:C3
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$bond:C0H $atom:C0 $atom:H0
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$bond:C1H1 $atom:C1 $atom:H11
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$bond:C1H2 $atom:C1 $atom:H12
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$bond:C1H3 $atom:C1 $atom:H13
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$bond:C2H1 $atom:C2 $atom:H21
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$bond:C2H2 $atom:C2 $atom:H22
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$bond:C2H3 $atom:C2 $atom:H23
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$bond:C3H1 $atom:C3 $atom:H31
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$bond:C3H2 $atom:C3 $atom:H32
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$bond:C3H3 $atom:C3 $atom:H33