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Adding kspace_modify diff option to select the PPPM differentiation method. 

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@8040 f3b2605a-c512-4ea7-a41b-209d697bcdaa
This commit is contained in:
pscrozi 2012-05-03 15:29:09 +00:00
parent 509f60f81f
commit ea6d8cbe23
2 changed files with 23 additions and 5 deletions
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13
doc/kspace_modify.html
View File

@ -17,7 +17,7 @@
</PRE>
<UL><LI>one or more keyword/value pairs may be listed
<LI>keyword = <I>mesh</I> or <I>order</I> or <I>gewald</I> or <I>slab</I>
<LI>keyword = <I>mesh</I> or <I>order</I> or <I>gewald</I> or <I>slab</I> or <I>compute</I> or <I>diff</I>
<PRE> <I>mesh</I> value = x y z
x,y,z = PPPM FFT grid size in each dimension
@ -30,6 +30,7 @@
volfactor = ratio of the total extended volume used in the
2d approximation compared with the volume of the simulation domain
<I>compute</I> value = <I>yes</I> or <I>no</I>
<I>diff</I> value = <I>ik</I> or <I>ad</I>
</PRE>
</UL>
@ -111,6 +112,14 @@ defining a <A HREF = "kspace_style.html">kspace_style</A>, but a Kspace-compatib
<A HREF = "pair_style.html">pair_style</A> requires a kspace_style to be defined.
This keyword gives you that option.
</P>
<P>The <I>diff</I> keyword specifies the differentiation scheme used by the
PPPM method to compute forces on particles given electrostatic
potentials on the PPPM mesh. The ik approach is the default that
performs differentiation in kspace, but requires 3 FFTs to transfer
the computed fields back to real space. The analytic differentiation,
or ad approach requires only 1 FFT, but requires a somewhat bigger
PPPM mesh to achieve the same accuracy as the ik approach.
</P>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
@ -120,7 +129,7 @@ This keyword gives you that option.
<P><B>Default:</B>
</P>
<P>The option defaults are mesh = 0 0 0, order = 5, force = -1.0, gewald
= 0.0, slab = 1.0, and compute = yes.
= 0.0, slab = 1.0, compute = yes, and diff = ik.
</P>
<HR>

15
doc/kspace_modify.txt
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@ -13,7 +13,7 @@ kspace_modify command :h3
kspace_modify keyword value ... :pre
one or more keyword/value pairs may be listed :ulb,l
keyword = {mesh} or {order} or {gewald} or {slab} :l
keyword = {mesh} or {order} or {gewald} or {slab} or {compute} or {diff} :l
{mesh} value = x y z
x,y,z = PPPM FFT grid size in each dimension
{order} value = N
@ -24,7 +24,8 @@ keyword = {mesh} or {order} or {gewald} or {slab} :l
{slab} value = volfactor
volfactor = ratio of the total extended volume used in the
2d approximation compared with the volume of the simulation domain
{compute} value = {yes} or {no} :pre
{compute} value = {yes} or {no}
{diff} value = {ik} or {ad} :pre
:ule
[Examples:]
@ -105,6 +106,14 @@ defining a "kspace_style"_kspace_style.html, but a Kspace-compatible
"pair_style"_pair_style.html requires a kspace_style to be defined.
This keyword gives you that option.
The {diff} keyword specifies the differentiation scheme used by the
PPPM method to compute forces on particles given electrostatic
potentials on the PPPM mesh. The ik approach is the default that
performs differentiation in kspace, but requires 3 FFTs to transfer
the computed fields back to real space. The analytic differentiation,
or ad approach requires only 1 FFT, but requires a somewhat bigger
PPPM mesh to achieve the same accuracy as the ik approach.
[Restrictions:] none
[Related commands:]
@ -114,7 +123,7 @@ This keyword gives you that option.
[Default:]
The option defaults are mesh = 0 0 0, order = 5, force = -1.0, gewald
= 0.0, slab = 1.0, and compute = yes.
= 0.0, slab = 1.0, compute = yes, and diff = ik.
:line