diff --git a/doc/src/pair_mesocnt.rst b/doc/src/pair_mesocnt.rst new file mode 100644 index 0000000000..6d70c767d6 --- /dev/null +++ b/doc/src/pair_mesocnt.rst @@ -0,0 +1,158 @@ +.. index:: pair\_style mesocnt + +pair\_style mesocnt command +=========================== + +Syntax +"""""" + + +.. parsed-literal:: + + pair_style mesocnt + +Examples +"""""""" + + +.. parsed-literal:: + + pair_style mesocnt + pair_coeff \* \* 10_10.cnt + +Description +""""""""""" + +Style *mesocnt* implements a mesoscopic potential +for the interaction of carbon nanotubes (CNTs). In this potential, +CNTs are modelled as chains of cylindrical segments in which +each infinitesimal surface element interacts with all other +CNT surface elements with the Lennard-Jones (LJ) term adopted from +the :doc:`airebo ` style. The interaction energy +is then computed by integrating over the surfaces of all interacting +CNTs. + +The potential is based on interactions between one cylindrical +segment and infinitely or semi-infinitely long CNTs as described +in :ref:`(Volkov1) `. Chains of segments are +converted to these (semi-)infinite CNTs bases on an approximate +chain approach outlined in :ref:`(Volkov2) `. +This allows to simplify the computation of the interactions +significantly and reduces the computational times to the +same order of magnitude as for regular bead spring models +where beads interact with the standard :doc:`pair\_lj/cut ` +potential. + +In LAMMPS, cylindrical segments are represented by bonds. Each +segment is defined by its two end points ("nodes") which correspond +to atoms in LAMMPS. For the exact functional form of the potential +and implementation details, the reader is referred to the +original papers :ref:`(Volkov1) ` and +:ref:`(Volkov2) `. + +The potential requires tabulated data provided in a single ASCII +text file specified in the :doc:`pair\_coeff ` command. +The first line of the file provides a time stamp and +general information. The second line lists four integers giving +the number of data points provided in the subsequent four +data tables. The third line lists four floating point numbers: +the CNT radius R, the LJ parameter sigma and two numerical +parameters delta1 and delta2. These four parameters are given +in Angstroms. This is followed by four data tables each separated +by a single empty line. The first two tables have two columns +and list the parameters uInfParallel and Gamma respectively. +The last two tables have three columns giving data on a quadratic +array and list the parameters Phi and uSemiParallel respectively. +uInfParallel and uSemiParallel are given in eV/Angstrom, Phi is +given in eV and Gamma is unitless. + +Potential files for CNTs can be readily generated using the freely +available code provided on + +https://github.com/phankl/cntpot + +Using the same approach, it should also be possible to +generate potential files for other 1D systems such as +boron nitride nanotubes. + +.. note:: + + LAMMPS comes with one *mesocnt* style potential file + where the default number of data points per table is 1001. + This is sufficient for NVT simulations. For proper energy + conservation, we recommend using a potential file where + the resolution for Phi is at least 2001 data points. + +.. note:: + + The *mesocnt* style requires CNTs to be represented + as a chain of atoms connected by bonds. Atoms need + to be numbered consecutively within one chain. + Atoms belonging to different CNTs need to be assigned + different molecule IDs. + +A full summary of the method and LAMMPS implementation details +is expected to soon become available in Computer Physics +Communications. + + +---------- + + +**Mixing, shift, table, tail correction, restart, rRESPA info**\ : + +This pair style does not support mixing. + +This pair style does not support the :doc:`pair\_modify ` +shift, table, and tail options. + +The mesocnt pair style do not write their information to :doc:`binary restart files `, since it is stored in tabulated potential files. +Thus, you need to re-specify the pair\_style and pair\_coeff commands in +an input script that reads a restart file. + +These pair style can only be used via the *pair* keyword of the +:doc:`run\_style respa ` command. They do not support the +*inner*\ , *middle*\ , *outer* keywords. + + +---------- + + +Restrictions +"""""""""""" + + +The mesocnt pair style is part of the USER-MISC package. It is only +enabled if LAMMPS was built with that package. See the :doc:`Build package ` doc page for more info. + +This pair potential requires the :doc:`newton ` setting to be +"on" for pair interactions. + +Related commands +"""""""""""""""" + +:doc:`pair\_coeff ` + +**Default:** none + + +---------- + + +.. _Volkov1: + + + +**(Volkov1)** Volkov and Zhigilei, J Phys Chem C, 114, 5513 (2010). + +.. _Volkov2: + + + +**(Volkov2)** Volkov, Simov and Zhigilei, APS Meeting Abstracts, +Q31.013 (2008). + + +.. _lws: http://lammps.sandia.gov +.. _ld: Manual.html +.. _lc: Commands_all.html