(be958284) · Commits · 郑智淋 / lammps

doc/fix_press_berendsen.html

+20 −3

Original line number	Diff line number	Diff line
		@@ -35,9 +35,10 @@
		</PRE>
		<LI>zero or more keyword/value pairs may be appended

		<LI>keyword = <I>dilate</I>
		<LI>keyword = <I>dilate</I> or <I>modulus</I>

		<PRE> <I>dilate</I> value = <I>all</I> or <I>partial</I>
		<I>modulus</I> value = bulk modulus of system (pressure units)
		</PRE>

		</UL>
		@@ -120,6 +121,21 @@ which pressure is relaxed. For example, a value of 1000.0 means to
		relax the pressure in a timespan of (roughly) 1000 time units (tau or
		fmsec or psec - see the <A HREF = "units.html">units</A> command).
		</P>
		<P>IMPORTANT NOTE: The relaxation time is actually also a function of the
		bulk modulus of the system (inverse of isothermal compressibility).
		The bulk modulus has units of pressure and is the amount of pressure
		that would need to be applied (isotropically) to reduce the volume of
		the system by a factor of 2. The bulk modulus can be set via the
		keyword <I>modulus</I>. The <I>Pdamp</I> parameter is effectively multiplied by
		the bulk modulus, so if the pressure is relaxing faster than expected
		or desired, increasing the bulk modulus has the same effect as
		increasing <I>Pdamp</I>. The converse is also true. LAMMPS does not
		attempt to guess a correct value of the bulk modulus; it just uses
		10.0 as a default value which is about right for a Lennard-Jones
		liquid, but will be way off for other materials and way too small for
		solids. Thus you should experiment to find appropriate values of
		<I>Pdamp</I> and/or the <I>modulus</I> when using this fix.
		</P>
		<HR>

		<P>This fix computes a temperature and pressure each timestep. To do
		@@ -183,7 +199,8 @@ npt</A>, <A HREF = "fix_temp_berendsen.html">fix temp/berendsen</A>,
		</P>
		<P><B>Default:</B>
		</P>
		<P>The keyword defaults are dilate = all.
		<P>The keyword defaults are dilate = all, modulus = 10.0 in units of
		pressure for whatever <A HREF = "units.html">units</A> are defined.
		</P>
		<HR>

doc/fix_press_berendsen.txt

+20 −3

Original line number	Diff line number	Diff line
		@@ -28,8 +28,9 @@ p-style = {xyz} or {xy} or {yz} or {xz} or {aniso} :l
		Pdamp = pressure damping parameter (time units) :pre

		zero or more keyword/value pairs may be appended :l
		keyword = {dilate} :l
		{dilate} value = {all} or {partial} :pre
		keyword = {dilate} or {modulus} :l
		{dilate} value = {all} or {partial}
		{modulus} value = bulk modulus of system (pressure units) :pre
		:ule

		[Examples:]
		@@ -111,6 +112,21 @@ which pressure is relaxed. For example, a value of 1000.0 means to
		relax the pressure in a timespan of (roughly) 1000 time units (tau or
		fmsec or psec - see the "units"_units.html command).

		IMPORTANT NOTE: The relaxation time is actually also a function of the
		bulk modulus of the system (inverse of isothermal compressibility).
		The bulk modulus has units of pressure and is the amount of pressure
		that would need to be applied (isotropically) to reduce the volume of
		the system by a factor of 2. The bulk modulus can be set via the
		keyword {modulus}. The {Pdamp} parameter is effectively multiplied by
		the bulk modulus, so if the pressure is relaxing faster than expected
		or desired, increasing the bulk modulus has the same effect as
		increasing {Pdamp}. The converse is also true. LAMMPS does not
		attempt to guess a correct value of the bulk modulus; it just uses
		10.0 as a default value which is about right for a Lennard-Jones
		liquid, but will be way off for other materials and way too small for
		solids. Thus you should experiment to find appropriate values of
		{Pdamp} and/or the {modulus} when using this fix.

		:line

		This fix computes a temperature and pressure each timestep. To do
		@@ -173,7 +189,8 @@ npt"_fix_npt.html, "fix temp/berendsen"_fix_temp_berendsen.html,

		[Default:]

		The keyword defaults are dilate = all.
		The keyword defaults are dilate = all, modulus = 10.0 in units of
		pressure for whatever "units"_units.html are defined.

		:line

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