bond_style_fene_expand.txt
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bond_style_fene_expand.txt
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			bond_style fene/expand command :h3

			[Syntax:]

			bond_style fene/expand :pre

			[Examples:]

			bond_style fene/expand
			bond_coeff 1 30.0 1.5 1.0 1.0 0.5 :pre

			[Description:]

			The {fene/expand} bond style uses the potential

			:c,image(Eqs/bond_fene_expand.jpg)

			to define a finite extensible nonlinear elastic (FENE) potential
			"(Kremer)"_#Kremer, used for bead-spring polymer models. The first
			term is attractive, the 2nd Lennard-Jones term is repulsive.

			The {fene/expand} bond style is similar to {fene} except that an extra
			shift factor of delta (positive or negative) is added to {r} to
			effectively change the bead size of the bonded atoms. The first term
			now extends to R0 + delta and the 2nd term is cutoff at 2^(1/6) sigma
			+ delta.

			The following coefficients must be defined for each bond type via the
			"bond_coeff"_bond_coeff.html command as in the example above, or in
			the data file or restart files read by the "read_data"_read_data.html
			or "read_restart"_read_restart.html commands:

			K (energy/distance^2)
			R0 (distance)
			epsilon (energy)
			sigma (distance)
			delta (distance) :ul

			[Restrictions:] none

			[Related commands:]

			"bond_coeff"_bond_coeff.html, "delete_bonds"_delete_bonds.html

			[Default:] none

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			:link(Kremer)
			[(Kremer)] Kremer, Grest, J Chem Phys, 92, 5057 (1990).