2006-09-22 00:22:34 +08:00
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<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
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<HR>
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<H3>angle_style charmm command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>angle_style charmm
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</PRE>
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<P><B>Examples:</B>
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</P>
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<PRE>angle_style charmm
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angle_coeff 1 300.0 107.0 50.0 3.0
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>The <I>charmm</I> angle style uses the potential
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</P>
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<CENTER><IMG SRC = "Eqs/angle_charmm.jpg">
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</CENTER>
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<P>with an additional Urey_Bradley term based on the distance <I>r</I> between
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the 1st and 3rd atoms in the angle. K, theta0, Kub, and Rub are
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coefficients defined for each angle type.
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</P>
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2006-09-28 03:12:31 +08:00
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<P>See <A HREF = "#MacKerell">(MacKerell)</A> for a description of the CHARMM force
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field.
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</P>
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2006-09-22 00:22:34 +08:00
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<P>The following coefficients must be defined for each angle type via the
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<A HREF = "angle_coeff.html">angle_coeff</A> command as in the example above, or in
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the data file or restart files read by the <A HREF = "read_data.html">read_data</A>
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or <A HREF = "read_restart.html">read_restart</A> commands:
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</P>
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<UL><LI>K (energy/radian^2)
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<LI>theta0 (degrees)
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<LI>K_ub (energy/distance^2)
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<LI>r_ub (distance)
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</UL>
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<P>Theta0 is specified in degrees, but LAMMPS converts it to radians
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internally; hence the units of K are in energy/radian^2.
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</P>
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2007-06-25 22:36:36 +08:00
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<P><B>Restrictions:</B>
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</P>
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<P>This angle style can only be used if LAMMPS was built with the
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2011-08-27 02:53:00 +08:00
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MOLECULAR package (which it is by default). See the <A HREF = "Section_start.html#start_3">Making
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2007-06-25 22:36:36 +08:00
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LAMMPS</A> section for more info on packages.
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2006-09-22 00:22:34 +08:00
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "angle_coeff.html">angle_coeff</A>
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</P>
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<P><B>Default:</B> none
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</P>
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2006-09-28 03:12:31 +08:00
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<HR>
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<A NAME = "MacKerell"></A>
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<P><B>(MacKerell)</B> 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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</P>
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2006-09-22 00:22:34 +08:00
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</HTML>
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