    heme_all.in         Heme-his prep file, all atom
    frcmod.hemall	Additional ff params, all atom
    heme_uni.in         Heme-his prep file, united atom
    frcmod.hemuni	Additional ff params, united atom

Use these carefully, since they are not part of the "standard"
AMBER distribution.  Contact David Case (case@scripps.edu) if
you have questions about how these were generated.  The heavy
atom names for the heme ring follow Brookhaven ideas, but the
protons are named according to a local, nmr-based convention.
For historical reasons, the united atom parameters are set up for
a deoxy heme, whereas the all-atom frcmod file is set up for a
ligated heme; you will want to carefully study these before
using them.

Chris Bayly of Merck added corrections to heme_all.in, changing
some atom names, also to frcmod.hemall, deleting the flexible 
water and Cl parameters, which are as follows:

BOND
OW-HW  529.6       0.9572      Pettitt force constant, TIP3 geom.
HW-HW   38.25      1.5136      Pettitt force constant, TIP3 geom.

ANGLE
HW-OW-HW    34.05     104.52           Pettitt force constant
OW-HW-HW    0.0        90.0

HBOND
  HW  OW   225.     0000.                                4.

NONBON
  HW       1.00       .020
  CL       2.223     0.107     0.0

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