diff --git a/doc/pair_srp.html b/doc/pair_srp.html index af2a3218c..7761a0bfd 100644 --- a/doc/pair_srp.html +++ b/doc/pair_srp.html @@ -1,164 +1,170 @@ <HTML> <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> </CENTER> <HR> <H3>pair_style srp command </H3> <P><B>Syntax:</B> </P> <P>pair_style srp cutoff bond_type dist keyword value ... </P> <UL><LI>cutoff = global cutoff for SRP interactions (distance units) <LI>bond_type = bond type to apply SRP interactions -<LI>dist = <I>min</I> or <I>mid</I> +<LI>distance = <I>min</I> or <I>mid</I> <LI>zero or more keyword/value pairs may be appended <LI>keyword = <I>exclude</I> <PRE> <I>exclude</I> value = <I>yes</I> or <I>no</I> </PRE> </UL> <P><B>Examples:</B> </P> <PRE>pair_style hybrid dpd 1.0 1.0 12345 srp 0.8 1 mid exclude yes pair_coeff 1 1 dpd 60.0 4.5 1.0 pair_coeff 1 2 none pair_coeff 2 2 srp 100.0 0.8 </PRE> -<PRE>pair_style hybrid srp 0.8 1 mid exclude yes +<PRE>pair_style hybrid dpd 1.0 1.0 12345 srp 0.8 1 min exclude yes +pair_coeff 1 1 dpd 60.0 50 1.0 +pair_coeff 1 2 none +pair_coeff 2 2 srp 40.0 +</PRE> +<PRE>pair_style hybrid srp 0.8 2 mid pair_coeff 1 1 none pair_coeff 1 2 none pair_coeff 2 2 srp 100.0 0.8 </PRE> <P><B>Description:</B> </P> <P>Style <I>srp</I> computes a soft segmental repulsive potential (SRP) that acts between pairs of bonds. This potential is useful for preventing bonds from passing through one another when a soft non-bonded potential acts between beads in, for example, DPD polymer chains. An example input script that uses this command is provided in examples/USER/srp. </P> <P>Bonds of type <I>btype</I> interact with one another through a bond-pairwise potential, such that the force on bond <I>i</I> due to bond <I>j</I> is as follows </P> <CENTER><IMG SRC = "Eqs/pair_srp1.jpg"> </CENTER> <P>where <I>r</I> and <I>rij</I> are the distance and unit vector between the two bonds. The <I>mid</I> option computes <I>r</I> and <I>rij</I> from the midpoint distance between bonds. The <I>min</I> option computes <I>r</I> and <I>rij</I> from the minimum distance between bonds. The force acting on a bond is mapped onto the two bond atoms according to the lever rule, </P> <CENTER><IMG SRC = "Eqs/pair_srp2.jpg"> </CENTER> <P>where <I>L</I> is the normalized distance from the atom to the point of closest approach of bond <I>i</I> and <I>j</I>. The <I>mid</I> option takes <I>L</I> as 0.5 for each interaction as described in <A HREF = "#Sirk">(Sirk)</A>. </P> <P>The following coefficients must be defined via the <A HREF = "pair_coeff.html">pair_coeff</A> command as in the examples above, or in the data file or restart file read by the <A HREF = "read_data.html">read_data</A> or <A HREF = "read_restart.html">read_restart</A> commands: </P> <UL><LI><I>C</I> (force units) -<LI><I>Rc</I> (distance units) +<LI><I>rc</I> (distance units) </UL> <P>The last coefficient is optional. If not specified, the global cutoff is used. </P> <P>IMPORTANT NOTE: Pair style srp considers each bond of type <I>btype</I> as a fictitious particle of type <I>bptype</I>, where <I>bptype</I> is the largest atom type in the system. These "bond particles" are inserted at the beginning of the run, and serve as placeholders that define the position of the bonds. This allows neighbor lists to be constructed and pairwise interactions to be computed in almost the same way as is done for point particles. Because bonds interact only with other bonds, <A HREF = "pair_hybrid.html">pair_style hybrid</A> should be used to turn off interactions between atom type <I>bptype</I> and all other types of atoms. An error will be flagged if <A HREF = "pair_hybrid.html">pair_style hybrid</A> is not used. Further, only bond particles should be given an atom type of <I>bptype</I>; a check is done at the beginning of the run to ensure there are no regular atoms of <I>bptype</I>. </P> <P>The optional <I>exclude</I> keyword determines if forces are computed between first neighbor (directly connected) bonds. For a setting of -<I>yes</I> they are, for <I>no</I> they are not. +<I>no</I>, first neighbor forces are computed; for <I>yes</I> they are not computed. A setting of <I>no</I> +cannot be used with the <I>min</I> option for distance calculation because the the minimum distance between +directly connected bonds is zero. </P> <P>Pair style <I>srp</I> turns off normalization of thermodynamic properties by particle number, as if the command <A HREF = "thermo_modify.html">thermo_modify norm -no</A> had been issued. A warning will be given if -this setting is overridden in the input script. +no</A> had been issued. </P> <P>The pairwise energy associated with style <I>srp</I> is shifted to be zero -at the cutoff distance <I>Rc</I>. +at the cutoff distance <I>rc</I>. </P> <HR> <P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>: </P> <P>This pair styles does not support mixing. </P> <P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A> shift option for the energy of the pair interaction. Note that as discussed above, the energy term is already shifted to be 0.0 at the cutoff distance <I>rc</I>. </P> <P>The <A HREF = "pair_modify.html">pair_modify</A> table option is not relevant for this pair style. </P> <P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A> tail option for adding long-range tail corrections to energy and pressure. </P> <P>This pair style writes global and per-atom information to <A HREF = "restart.html">binary restart files</A>. Pair srp should be used with <A HREF = "pair_hybrid.html">pair_style hybrid</A>, thus the pair_coeff commands need to be specified in the input script when reading a restart file. </P> <P>This pair style can only be used via the <I>pair</I> keyword of the <A HREF = "run_style.html">run_style respa</A> command. It does not support the <I>inner</I>, <I>middle</I>, <I>outer</I> keywords. </P> <HR> <P><B>Restrictions:</B> </P> <P>This pair style is part of the USER-MISC package. It is only enabled if LAMMPS was built with that package. See the Making LAMMPS section for more info. </P> <P>This pair style must be used with <A HREF = "pair_hybrid.html">pair_style hybrid</A>. </P> <P>This pair style requires the <A HREF = "newton.html">newton</A> command to be <I>on</I> for non-bonded interactions. </P> <P><B>Related commands:</B> </P> <P><A HREF = "pair_hybrid.html">pair_style hybrid</A>, <A HREF = "pair_coeff.html">pair_coeff</A>, <A HREF = "pair_dpd.html">pair dpd</A> </P> <P><B>Default:</B> </P> <P>The default keyword value is exclude = yes. </P> <HR> <A NAME = "Sirk"></A> -<P><B>(Sirk)</B> Sirk TW, Slizoberg YR, Brennan JK, Lisal M, Andzelm JW, J +<P><B>(Sirk)</B> Sirk TW, Sliozberg YR, Brennan JK, Lisal M, Andzelm JW, J Chem Phys, 136 (13) 134903, 2012. </P> </HTML> diff --git a/doc/pair_srp.txt b/doc/pair_srp.txt index 26eb921b1..2944979a7 100644 --- a/doc/pair_srp.txt +++ b/doc/pair_srp.txt @@ -1,152 +1,158 @@ "LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c :link(lws,http://lammps.sandia.gov) :link(ld,Manual.html) :link(lc,Section_commands.html#comm) :line pair_style srp command :h3 [Syntax:] pair_style srp cutoff bond_type dist keyword value ... cutoff = global cutoff for SRP interactions (distance units) :ulb,l bond_type = bond type to apply SRP interactions :l -dist = {min} or {mid} :l +distance = {min} or {mid} :l zero or more keyword/value pairs may be appended :l keyword = {exclude} :l {exclude} value = {yes} or {no} :pre :ule [Examples:] pair_style hybrid dpd 1.0 1.0 12345 srp 0.8 1 mid exclude yes pair_coeff 1 1 dpd 60.0 4.5 1.0 pair_coeff 1 2 none pair_coeff 2 2 srp 100.0 0.8 :pre -pair_style hybrid srp 0.8 1 mid exclude yes +pair_style hybrid dpd 1.0 1.0 12345 srp 0.8 1 min exclude yes +pair_coeff 1 1 dpd 60.0 50 1.0 +pair_coeff 1 2 none +pair_coeff 2 2 srp 40.0 :pre + +pair_style hybrid srp 0.8 2 mid pair_coeff 1 1 none pair_coeff 1 2 none pair_coeff 2 2 srp 100.0 0.8 :pre [Description:] Style {srp} computes a soft segmental repulsive potential (SRP) that acts between pairs of bonds. This potential is useful for preventing bonds from passing through one another when a soft non-bonded potential acts between beads in, for example, DPD polymer chains. An example input script that uses this command is provided in examples/USER/srp. Bonds of type {btype} interact with one another through a bond-pairwise potential, such that the force on bond {i} due to bond {j} is as follows :c,image(Eqs/pair_srp1.jpg) where {r} and {rij} are the distance and unit vector between the two bonds. The {mid} option computes {r} and {rij} from the midpoint distance between bonds. The {min} option computes {r} and {rij} from the minimum distance between bonds. The force acting on a bond is mapped onto the two bond atoms according to the lever rule, :c,image(Eqs/pair_srp2.jpg) where {L} is the normalized distance from the atom to the point of closest approach of bond {i} and {j}. The {mid} option takes {L} as 0.5 for each interaction as described in "(Sirk)"_#Sirk. The following coefficients must be defined via the "pair_coeff"_pair_coeff.html command as in the examples above, or in the data file or restart file read by the "read_data"_read_data.html or "read_restart"_read_restart.html commands: {C} (force units) -{Rc} (distance units) :ul +{rc} (distance units) :ul The last coefficient is optional. If not specified, the global cutoff is used. IMPORTANT NOTE: Pair style srp considers each bond of type {btype} as a fictitious particle of type {bptype}, where {bptype} is the largest atom type in the system. These "bond particles" are inserted at the beginning of the run, and serve as placeholders that define the position of the bonds. This allows neighbor lists to be constructed and pairwise interactions to be computed in almost the same way as is done for point particles. Because bonds interact only with other bonds, "pair_style hybrid"_pair_hybrid.html should be used to turn off interactions between atom type {bptype} and all other types of atoms. An error will be flagged if "pair_style hybrid"_pair_hybrid.html is not used. Further, only bond particles should be given an atom type of {bptype}; a check is done at the beginning of the run to ensure there are no regular atoms of {bptype}. The optional {exclude} keyword determines if forces are computed between first neighbor (directly connected) bonds. For a setting of -{yes} they are, for {no} they are not. +{no}, first neighbor forces are computed; for {yes} they are not computed. A setting of {no} +cannot be used with the {min} option for distance calculation because the the minimum distance between +directly connected bonds is zero. Pair style {srp} turns off normalization of thermodynamic properties by particle number, as if the command "thermo_modify norm -no"_thermo_modify.html had been issued. A warning will be given if -this setting is overridden in the input script. +no"_thermo_modify.html had been issued. The pairwise energy associated with style {srp} is shifted to be zero -at the cutoff distance {Rc}. +at the cutoff distance {rc}. :line [Mixing, shift, table, tail correction, restart, rRESPA info]: This pair styles does not support mixing. This pair style does not support the "pair_modify"_pair_modify.html shift option for the energy of the pair interaction. Note that as discussed above, the energy term is already shifted to be 0.0 at the cutoff distance {rc}. The "pair_modify"_pair_modify.html table option is not relevant for this pair style. This pair style does not support the "pair_modify"_pair_modify.html tail option for adding long-range tail corrections to energy and pressure. This pair style writes global and per-atom information to "binary restart files"_restart.html. Pair srp should be used with "pair_style hybrid"_pair_hybrid.html, thus the pair_coeff commands need to be specified in the input script when reading a restart file. This pair style can only be used via the {pair} keyword of the "run_style respa"_run_style.html command. It does not support the {inner}, {middle}, {outer} keywords. :line [Restrictions:] This pair style is part of the USER-MISC package. It is only enabled if LAMMPS was built with that package. See the Making LAMMPS section for more info. This pair style must be used with "pair_style hybrid"_pair_hybrid.html. This pair style requires the "newton"_newton.html command to be {on} for non-bonded interactions. [Related commands:] "pair_style hybrid"_pair_hybrid.html, "pair_coeff"_pair_coeff.html, "pair dpd"_pair_dpd.html [Default:] The default keyword value is exclude = yes. :line :link(Sirk) -[(Sirk)] Sirk TW, Slizoberg YR, Brennan JK, Lisal M, Andzelm JW, J +[(Sirk)] Sirk TW, Sliozberg YR, Brennan JK, Lisal M, Andzelm JW, J Chem Phys, 136 (13) 134903, 2012.