.. index:: pair_style sph/idealgas pair_style sph/idealgas command =============================== Syntax """""" .. parsed-literal:: pair_style sph/idealgas Examples """""""" .. parsed-literal:: pair_style sph/idealgas pair_coeff * * 1.0 2.4 Description """"""""""" The sph/idealgas style computes pressure forces between particles according to the ideal gas equation of state: .. image:: Eqs/pair_sph_ideal.jpg :align: center where gamma = 1.4 is the heat capacity ratio, rho is the local density, and e is the internal energy per unit mass. This pair style also computes Monaghan's artificial viscosity to prevent particles from interpentrating :ref:`(Monaghan) `. See `this PDF guide `_ to using SPH in LAMMPS. The following coefficients must be defined for each pair of atoms types via the :doc:`pair_coeff ` command as in the examples above. * nu artificial viscosity (no units) * h kernel function cutoff (distance units) ---------- **Mixing, shift, table, tail correction, restart, rRESPA info**\ : This style does not support mixing. Thus, coefficients for all I,J pairs must be specified explicitly. This style does not support the :doc:`pair_modify ` shift, table, and tail options. This style does not write information to :doc:`binary restart files `. Thus, you need to re-specify the pair_style and pair_coeff commands in an input script that reads a restart file. This style can only be used via the *pair* keyword of the :doc:`run_style respa ` command. It does not support the *inner*\ , *middle*\ , *outer* keywords. Restrictions """""""""""" This pair style is part of the USER-SPH package. It is only enabled if LAMMPS was built with that package. See the :ref:`Making LAMMPS ` section for more info. Related commands """""""""""""""" :doc:`pair_coeff `, pair_sph/rhosum **Default:** none ---------- .. _Monoghan: **(Monaghan)** Monaghan and Gingold, Journal of Computational Physics, 52, 374-389 (1983). .. _lws: http://lammps.sandia.gov .. _ld: Manual.html .. _lc: Section_commands.html#comm