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274 lines
13 KiB
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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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<H3>thermo_style command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>thermo_style style args
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</PRE>
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<UL><LI>style = <I>one</I> or <I>multi</I> or <I>custom</I>
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<LI>args = list of arguments for a particular style
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<PRE> <I>one</I> args = none
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<I>multi</I> args = none
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<I>custom</I> args = list of attributes
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possible attributes = step, atoms, cpu, temp, press,
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pe, ke, etotal, enthalpy,
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evdwl, ecoul, epair, ebond, eangle, edihed, eimp,
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emol, elong, etail,
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vol, lx, ly, lz, xlo, xhi, ylo, yhi, zlo, zhi,
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xy, xz, yz, xlat, ylat, zlat,
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pxx, pyy, pzz, pxy, pxz, pyz,
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c_ID, c_ID[I], c_ID[I][J],
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f_ID, f_ID[I], f_ID[I][J],
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v_name
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step = timestep
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atoms = # of atoms
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cpu = elapsed CPU time
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temp = temperature
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press = pressure
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pe = total potential energy
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ke = kinetic energy
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etotal = total energy (pe + ke)
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enthalpy = enthalpy (etotal + press*vol)
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evdwl = VanderWaal pairwise energy
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ecoul = Coulombic pairwise energy
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epair = pairwise energy (evdwl + ecoul + elong + etail)
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ebond = bond energy
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eangle = angle energy
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edihed = dihedral energy
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eimp = improper energy
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emol = molecular energy (ebond + eangle + edihed + eimp)
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elong = long-range kspace energy
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etail = VanderWaal energy long-range tail correction
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vol = volume
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lx,ly,lz = box lengths in x,y,z
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xlo,xhi,ylo,yhi,zlo,zhi = box boundaries
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xy,xz,yz = box tilt for triclinic (non-orthogonal) simulation boxes
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xlat,ylat,zlat = lattice spacings as calculated by <A HREF = "lattice.html">lattice</A> command
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pxx,pyy,pzz,pxy,pxz,pyz = 6 components of pressure tensor
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c_ID = global scalar value calculated by a compute with ID
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c_ID[I] = Ith component of global vector calculated by a compute with ID
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c_ID[I][J] = I,J component of global array calculated by a compute with ID
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f_ID = global scalar value calculated by a fix with ID
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f_ID[I] = Ith component of global vector calculated by a fix with ID
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f_ID[I][J] = I,J component of global array calculated by a fix with ID
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v_name = scalar value calculated by an equal-style variable with name
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</PRE>
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>thermo_style multi
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thermo_style custom step temp pe etotal press vol
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thermo_style custom step temp etotal c_myTemp v_abc
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Set the style and content for printing thermodynamic data to the
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screen and log file.
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</P>
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<P>Style <I>one</I> prints a one-line summary of thermodynamic info that is
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the equivalent of "thermo_style custom step temp epair emol etotal
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press". The line contains only numeric values.
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</P>
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<P>Style <I>multi</I> prints a multiple-line listing of thermodynamic info
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that is the equivalent of "thermo_style custom etotal ke temp pe ebond
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eangle edihed eimp evdwl ecoul elong press". The listing contains
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numeric values and a string ID for each quantity.
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</P>
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<P>Style <I>custom</I> is the most general setting and allows you to specify
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which of the keywords listed above you want printed on each
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thermodynamic timestep. Note that the keywords c_ID, f_ID, v_name are
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references to <A HREF = "compute.html">computes</A>, <A HREF = "fix.html">fixes</A>, and
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equal-style <A HREF = "variable.html"">variables</A> that have been defined
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elsewhere in the input script or can even be new styles which users
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have added to LAMMPS (see the <A HREF = "Section_modify.html">Section_modify</A>
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section of the documentation). Thus the <I>custom</I> style provides a
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flexible means of outputting essentially any desired quantity as a
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simulation proceeds.
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</P>
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<P>All styles except <I>custom</I> have <I>vol</I> appended to their list of
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outputs if the simulation box volume changes during the simulation.
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</P>
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<P>The values printed by the various keywords are instantaneous values,
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calculated on the current timestep. Time-averaged quantities, which
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include values from previous timesteps, can be output by using the
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f_ID keyword and accessing a fix that does time-averaging such as the
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<A HREF = "fix_ave_time.html">fix ave/time</A> command.
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</P>
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<P>Options invoked by the <A HREF = "thermo_modify.html">thermo_modify</A> command can
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be used to set the one- or multi-line format of the print-out, the
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normalization of thermodynamic output (total values versus per-atom
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values for extensive quantities (ones which scale with the number of
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atoms in the system), and the numeric precision of each printed value.
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</P>
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<P>IMPORTANT NOTE: When you use a "thermo_style" command, all
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thermodynamic settings are restored to their default values, including
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those previously set by a <A HREF = "thermo_modify.html">thermo_modify</A> command.
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Thus if your input script specifies a thermo_style command, you should
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use the thermo_modify command after it.
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</P>
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<HR>
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<P>Several of the thermodynamic quantities require a temperature to be
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computed: "temp", "press", "ke", "etotal", "enthalpy", "pxx etc". By
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default this is done by using a <I>temperature</I> compute which is created
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when LAMMPS starts up, as if this command had been issued:
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</P>
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<PRE>compute thermo_temp all temp
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</PRE>
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<P>See the <A HREF = "compute_temp.html">compute temp</A> command for details. Note
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that the ID of this compute is <I>thermo_temp</I> and the group is <I>all</I>.
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You can change the attributes of this temperature (e.g. its
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degrees-of-freedom) via the <A HREF = "compute_modify.html">compute_modify</A>
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command. Alternatively, you can directly assign a new compute (that
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calculates temperature) which you have defined, to be used for
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calculating any thermodynamic quantity that requires a temperature.
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This is done via the <A HREF = "thermo_modify.html">thermo_modify</A> command.
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</P>
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<P>Several of the thermodynamic quantities require a pressure to be
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computed: "press", "enthalpy", "pxx", etc. By default this is done by
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using a <I>pressure</I> compute which is created when LAMMPS starts up, as
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if this command had been issued:
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</P>
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<PRE>compute thermo_press all pressure thermo_temp
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</PRE>
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<P>See the <A HREF = "compute_pressure.html">compute pressure</A> command for details.
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Note that the ID of this compute is <I>thermo_press</I> and the group is
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<I>all</I>. You can change the attributes of this pressure via the
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<A HREF = "compute_modify.html">compute_modify</A> command. Alternatively, you can
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directly assign a new compute (that calculates pressure) which you
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have defined, to be used for calculating any thermodynamic quantity
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that requires a pressure. This is done via the
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<A HREF = "thermo_modify.html">thermo_modify</A> command.
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</P>
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<P>Several of the thermodynamic quantities require a potential energy to
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be computed: "pe", "etotal", "ebond", etc. This is done by using a
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<I>pe</I> compute which is created when LAMMPS starts up, as if this
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command had been issued:
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</P>
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<PRE>compute thermo_pe all pe
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</PRE>
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<P>See the <A HREF = "compute_pe.html">compute pe</A> command for details. Note that
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the ID of this compute is <I>thermo_pe</I> and the group is <I>all</I>. You can
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change the attributes of this potential energy via the
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<A HREF = "compute_modify.html">compute_modify</A> command.
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</P>
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<HR>
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<P>The kinetic energy of the system <I>ke</I> is inferred from the temperature
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of the system with 1/2 Kb T of energy for each degree of freedom.
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Thus, using different <A HREF = "compute.html">compute commands</A> for calculating
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temperature, via the <A HREF = "thermo_modify.html">thermo_modify temp</A> command,
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may yield different kinetic energies, since different computes that
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calculate temperature can subtract out different non-thermal
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components of velocity and/or include different degrees of freedom
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(translational, rotational, etc).
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</P>
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<P>The potential energy of the system <I>pe</I> will include contributions
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from fixes if the <A HREF = "fix_modify.html">fix_modify thermo</A> option is set
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for a fix that calculates such a contribution. For example, the <A HREF = "fix_wall_lj93">fix
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wall/lj93</A> fix calculates the energy of atoms
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interacting with the wall. See the doc pages for "individual fixes"
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to see which ones contribute.
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</P>
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<P>A long-range tail correction <I>etail</I> for the VanderWaal pairwise
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energy will be non-zero only if the <A HREF = "pair_modify.html">pair_modify
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tail</A> option is turned on. The <I>etail</I> contribution
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is included in <I>evdwl</I>, <I>pe</I>, and <I>etotal</I>, and the corresponding tail
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correction to the pressure is included in <I>press</I> and <I>pxx</I>, <I>pyy</I>,
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etc.
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</P>
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<HR>
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<P>The <I>c_ID</I> and <I>c_ID[I]</I> and <I>c_ID[I][J]</I> keywords allow global
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values calculated by a compute to be output. As discussed on the
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<A HREF = "compute.html">compute</A> doc page, computes can calculate global,
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per-atom, or local values. Only global values can be referenced by
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this command. However, per-atom compute values can be referenced in a
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<A HREF = "variable.html">variable</A> and the variable referenced by thermo_style
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custom, as discussed below.
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</P>
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<P>The ID in the keyword should be replaced by the actual ID of a compute
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that has been defined elsewhere in the input script. See the
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<A HREF = "compute.html">compute</A> command for details. If the compute calculates
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a global scalar, vector, or array, then the keyword formats with 0, 1,
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or 2 brackets will reference a scalar value from the compute.
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</P>
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<P>Note that some computes calculate "intensive" global quantities like
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temperature; others calculate "extensive" global quantities like
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kinetic energy that are summed over all atoms in the compute group.
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Intensive quantities are printed directly without normalization by
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thermo_style custom. Extensive quantities may be normalized by the
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total number of atoms in the simulation (NOT the number of atoms in
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the compute group) when output, depending on the <A HREF = "thermo_modify.html">thermo_modify
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norm</A> option being used.
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</P>
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<P>The <I>f_ID</I> and <I>f_ID[I]</I> and <I>f_ID[I][J]</I> keywords allow global
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values calculated by a fix to be output. As discussed on the
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<A HREF = "fix.html">fix</A> doc page, fixes can calculate global, per-atom, or
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local values. Only global values can be referenced by this command.
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However, per-atom fix values can be referenced in a
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<A HREF = "variable.html">variable</A> and the variable referenced by thermo_style
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custom, as discussed below.
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</P>
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<P>The ID in the keyword should be replaced by the actual ID of a fix
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that has been defined elsewhere in the input script. See the
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<A HREF = "fix.html">fix</A> command for details. If the fix calculates a global
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scalar, vector, or array, then the keyword formats with 0, 1, or 2
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brackets will reference a scalar value from the fix.
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</P>
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<P>Note that some fixes calculate "intensive" global quantities like
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timestep size; others calculate "extensive" global quantities like
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energy that are summed over all atoms in the fix group. Intensive
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quantities are printed directly without normalization by thermo_style
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custom. Extensive quantities may be normalized by the total number of
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atoms in the simulation (NOT the number of atoms in the fix group)
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when output, depending on the <A HREF = "thermo_modify.html">thermo_modify norm</A>
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option being used.
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</P>
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<P>The <I>v_name</I> keyword allow the current value of a variable to be
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output. The name in the keyword should be replaced by the actual name
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of the variable that has been defined elsewhere in the input script.
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Only equal-style variables can be referenced. See the
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<A HREF = "variable.html">variable</A> command for details. Variables of style
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<I>equal</I> can reference per-atom properties or thermodynamic keywords,
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or they can invoke other computes, fixes, or variables when evaluated,
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so this is a very general means of creating thermodynamic output.
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</P>
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<P>See <A HREF = "Section_modify.html">this section</A> for information on how to add
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new compute and fix styles to LAMMPS to calculate quantities that can
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then be referenced with these keywords to generate thermodynamic
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output.
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</P>
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<HR>
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<P><B>Restrictions:</B>
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</P>
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<P>This command must come after the simulation box is defined by a
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<A HREF = "read_data.html">read_data</A>, <A HREF = "read_restart.html">read_restart</A>, or
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<A HREF = "create_box.html">create_box</A> command.
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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 = "thermo.html">thermo</A>, <A HREF = "thermo_modify.html">thermo_modify</A>,
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<A HREF = "fix_modify.html">fix_modify</A>, <A HREF = "compute_temp.html">compute temp</A>,
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<A HREF = "compute_pressure.html">compute pressure</A>
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</P>
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<P><B>Default:</B>
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</P>
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<PRE>thermo_style one
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</PRE>
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</HTML>
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