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181
doc/pair_style_eam.html
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@ -25,13 +25,13 @@
</P>
<PRE>pair_style eam
pair_coeff * * cuu3
pair_coeff 1*3 1*3 niu3
pair_coeff 1*3 1*3 niu3.eam
</PRE>
<PRE>pair_style eam/alloy
pair_coeff * * nialhjea 1 2 1 1
pair_coeff * * ../potentials/nialhjea.eam.alloy Ni Al Ni Ni
</PRE>
<PRE>pair_style eam/fs
pair_coeff * * nial.fs 1 2 1 1
pair_coeff * * nialhjea.eam.fs Ni Al Ni Ni
</PRE>
<P><B>Description:</B>
</P>
@ -58,30 +58,32 @@ the "potentials" directory of the LAMMPS distribution.
</P>
<P>IMPORTANT NOTE: The <I>eam</I> style reads single-element EAM potentials in
the DYNAMO <I>funcfl</I> format. Either single element or alloy systems
can be modeled with <I>funcfl</I> files and style <I>eam</I>. For the alloy
case LAMMPS mixes the single-element potentials to produce alloy
potentials the same way that DYNAMO does. Alternatively, DYNAMO
<I>setfl</I> files can be used by LAMMPS to model alloy systems by invoking
the <I>eam/alloy</I> style as described below. <I>Setfl</I> files require no
mixing since they specify alloy interactions explicitly.
can be modeled using multiple <I>funcfl</I> files and style <I>eam</I>. For the
alloy case LAMMPS mixes the single-element potentials to produce alloy
potentials, the same way that DYNAMO does. Alternatively, a single
DYNAMO <I>setfl</I> file of Finnis/Sinclair EAM file can be used by LAMMPS
to model alloy systems by invoking the <I>eam/alloy</I> or <I>eam/fs</I> styles
as described below. These files require no mixing since they specify
alloy interactions explicitly.
</P>
<P>For style <I>eam</I>, potential values are read from a file that is in the
DYNAMO single-element <I>funcfl</I> format. If the DYNAMO file was created
by a Fortran program, it cannot have "D" values in it for exponents.
C only recognizes "e" or "E" for scientific notation.
</P>
<P>Note that unlike for other potentials, you do not set cutoffs for EAM
potentials in the pair_style or pair_coeff command; they are specified
in the EAM potential files.
<P>Note that unlike for other potentials, cutoffs for EAM potentials are
not set in the pair_style or pair_coeff command; they are specified in
the EAM potential files themselves.
</P>
<P>For style <I>eam</I> you must assign a potential file to each I,I pair of
atom types by using a single pair_coeff argument:
<P>For style <I>eam</I> a potential file must be assigned to each I,I pair of
atom types by using one or more pair_coeff commands, each with a
single argument:
</P>
<UL><LI>filename
</UL>
<P>Thus the following command
</P>
<PRE>pair_coeff *2 1*2 cuu3
<PRE>pair_coeff *2 1*2 cuu3.eam
</PRE>
<P>will read the cuu3 potential file and use the tabulated Cu values for
F, phi, rho that it contains for type pairs 1,1 and 2,2 (type pairs
@ -101,23 +103,35 @@ LAMMPS distribution, with the suffix ".eam". A DYNAMO single-element
<LI>line 3: Nrho, drho, Nr, dr, cutoff
</UL>
<P>On line 2, all values but the mass are ignored by LAMMPS. The mass is
in atomic mass units which is converted by LAMMPS to the appropriate
internal mass <A HREF = "units.html">units</A>. On line 3, Nrho and Nr are the
number of tabulated values in the subsequent arrays, drho and dr are
the spacing in density and distance space for the values in those
arrays, and the specified cutoff becomes the pairwise cutoff used by
LAMMPS for the potential. The units of dr are Angstroms; I'm not sure
of the units for drho - some measure of electron density.
in atomic mass units (g/cm^3) which is converted by LAMMPS to the
appropriate internal mass <A HREF = "units.html">units</A>. The cubic lattice
constant is in Angstroms. On line 3, Nrho and Nr are the number of
tabulated values in the subsequent arrays, drho and dr are the spacing
in density and distance space for the values in those arrays, and the
specified cutoff becomes the pairwise cutoff used by LAMMPS for the
potential. The units of dr are Angstroms; I'm not sure of the units
for drho - some measure of electron density.
</P>
<P>Following the 3 header lines are 3 arrays of tabulated values:
</P>
<UL><LI>embedding function F (Nrho values)
<LI>pair potential function phi (Nr values)
<LI>density function rho (Nr values)
<UL><LI>embedding function F(rho) (Nrho values)
<LI>effective charge function Z(r) (Nr values)
<LI>density function rho(r) (Nr values)
</UL>
<P>The values for each array can be listed as multiple values per line,
so long as each array starts on a new line. The individual values are
(for example) phi(r) for r = 0,dr,2*dr, ... (Nr-1)*dr.
so long as each array starts on a new line. For example, the
individual Z(r) values are for r = 0,dr,2*dr, ... (Nr-1)*dr.
</P>
<P>The units for the embedding function F are eV. The units for the
density function rho are the same as for drho (see above, electron
density). The units for the effective charge Z are "atomic charge" or
sqrt(Hartree * Bohr-radii). For 2 interacting atoms i,j this is used
by LAMMPS to compute the pair potential term in the EAM energy
expression as r*phi, in units of eV-Angstroms, via the formula
</P>
<PRE>r*phi = 27.2 * 0.529 * Zi * Zj
</PRE>
<P>where 1 Hartree = 27.2 eV and 1 Bohr = 0.529 Angstroms.
</P>
<HR>
@ -131,64 +145,76 @@ interactions. Thus they allow more generality than <I>funcfl</I> files for
modeling alloys.
</P>
<P>For style <I>eam/alloy</I>, potential values are read from a file that is
in the DYNAMO multi-element <I>setfl</I> format. If the DYNAMO file was
created by a Fortran program, it cannot have "D" values in it for
exponents. C only recognizes "e" or "E" for scientific notation.
in the DYNAMO multi-element <I>setfl</I> format, except that element names
(Ni, Cu, etc) are added to one of the lines in the file. If the
DYNAMO file was created by a Fortran program, it cannot have "D"
values in it for exponents. C only recognizes "e" or "E" for
scientific notation.
</P>
<P>Only one pair_coeff command can be used (one file). DYNAMO <I>setfl</I>
files contain information for M elements. These are mapped to LAMMPS
atom types by specifying N additional arguments after the filename,
where N is the number of LAMMPS atom types:
<P>Only one pair_coeff command can be used which specifies a single
<I>setfl</I> file. DYNAMO <I>setfl</I> files contain information for M
elements. These are mapped to LAMMPS atom types by specifying N
additional arguments after the filename, where N is the number of
LAMMPS atom types:
</P>
<UL><LI>filename
<LI>N values from 0 to M = mapping of <I>setfl</I> elements to atom types
<LI>N element names = mapping of <I>setfl</I> elements to atom types
</UL>
<P>As an example, the nialhjea <I>setfl</I> file has tabulated EAM values for
3 elements and their alloy interactions: Ni, Al, and H. If your
LAMMPS simulation has 4 atoms types and you want the 1st 3 to be Ni,
LAMMPS simulation had 4 atoms types and you wanted the 1st 3 to be Ni,
and the 4th to be Al, you would use the following pair_coeff command:
</P>
<PRE>pair_coeff * * nialhjea 1 1 1 2
<PRE>pair_coeff * * nialhjea.eam.alloy Ni Ni Ni Al
</PRE>
<P>The 1st 2 arguments must be * * so as to span all LAMMPS atom types.
The first three "1" values map LAMMPS atom types 1,2,3 to the 1st
element (Ni) in the <I>setfl</I> file. The final "2" value maps LAMMPS
atom type 4 to the 2nd element = Al. If a mapping value is "0", the
mapping is not performed. This can be used when an <I>eam/alloy</I>
potential is used as part of the <I>hybrid</I> pair style. The 0 values
are used as placeholders for atom types that will be used with other
potentials.
The first three Ni arguments map LAMMPS atom types 1,2,3 to the Ni
element in the <I>setfl</I> file. The final Al argument maps LAMMPS atom
type 4 to the Al element in the <I>setfl</I> file. If a mapping value is
specified as NULL, the mapping is not performed. This can be used
when an <I>eam/alloy</I> potential is used as part of the <I>hybrid</I> pair
style. The NULL values are placeholders for atom types that will be
used with other potentials.
</P>
<P><I>Setfl</I> files in the <I>potentials</I> directory of the LAMMPS distribution
have a ".eam.alloy" suffix. A DYNAMO multi-element <I>setfl</I> file is
formatted as follows:
</P>
<UL><LI>lines 1,2,3 = comments (ignored)
<LI>line 4: Nelements = # of elements in the file
<LI>line 4: Nelements Element1 Element2 ... ElementN
<LI>line 5: Nrho, drho, Nr, dr, cutoff
</UL>
<P>The meaning of the values in line 5 is the same as for the <I>funcfl</I>
file described above. Note that the cutoff is a global value, valid
for all pairwise interactions for all element pairings.
<P>In a DYNAMO <I>setfl</I> file, line 4 only lists Nelements = the # of
elements in the <I>setfl</I> file. For LAMMPS, the element name (Ni, Cu,
etc) of each element must be added to the line, in the order the
elements appear in the file.
</P>
<P>The meaning and units of the values in line 5 is the same as for the
<I>funcfl</I> file described above. Note that the cutoff (in Angstroms) is
a global value, valid for all pairwise interactions for all element
pairings.
</P>
<P>Following the 5 header lines are Nelements sections, one for each
element, each with the following format:
</P>
<UL><LI>line 1 = atomic number, mass, lattice constant, lattice type (e.g. FCC)
<LI>embedding function F (Nrho values)
<LI>density function rho (Nr values)
<LI>embedding function F(rho) (Nrho values)
<LI>density function rho(r) (Nr values)
</UL>
<P>As with the <I>funcfl</I> files, only the mass is used by LAMMPS from the 1st
line. The F and rho arrays are unique to a single element and are
formatted the same as in a <I>funcfl</I> file.
<P>As with the <I>funcfl</I> files, only the mass (g/cm^3) is used by LAMMPS
from the 1st line. The cubic lattice constant is in Angstroms. The F
and rho arrays are unique to a single element and have the same format
and units as in a <I>funcfl</I> file.
</P>
<P>Following the Nelements sections, values for the pair potential phi
arrays are listed for all i,j element pairs in the same format as
other arrays. Since these interactions are symmetric (i,j = j,i) only
phi arrays with i >= j are listed, in the following order: i,j =
<P>Following the Nelements sections, Nr values for each pair potential
phi(r) array are listed for all i,j element pairs in the same format
as other arrays. Since these interactions are symmetric (i,j = j,i)
only phi arrays with i >= j are listed, in the following order: i,j =
(1,1), (2,1), (2,2), (3,1), (3,2), (3,3), (4,1), ..., (Nelements,
Nelements). The tabulated values for each phi function are listed in
<I>setfl</I> files as r*phi, rather than as phi (in <I>funcfl</I> files).
Nelements). Unlike the effective charge array Z(r) in <I>funcfl</I> files,
the tabulated values for each phi function are listed in <I>setfl</I> files
directly as r*phi (in units of eV-Angstroms), since they are for atom
pairs.
</P>
<HR>
@ -216,32 +242,32 @@ potential is the same author's Fe-P FS potential
<A HREF = "#Ackland2">(Ackland2)</A>. Note that while FS potentials always specify
the embedding energy with a square root dependence on the total
density, the implementation in LAMMPS does not require that; the user
can tabulate any functional form he desires in the FS potential files.
can tabulate any functional form desired in the FS potential files.
</P>
<P>For style <I>eam/fs</I>, the form of the pair_coeff command is exactly the
same as for style <I>eam/alloy</I>, e.g.
</P>
<PRE>pair_coeff * * filename 1 1 1 2
<PRE>pair_coeff * * nialhjea.eam.fs Ni Ni Ni Al
</PRE>
<P>where there are N additional arguments after the filename, where N is
the number of LAMMPS atom types. The N values determine the mapping
of LAMMPS atom types to EAM elements in the file, as described above
for style <I>eam/alloy</I>. As with <I>eam/alloy</I>, if a mapping value is
"0", the mapping is not performed. This can be used when an <I>eam/fs</I>
potential is used as part of the <I>hybrid</I> pair style. The 0 values
NULL, the mapping is not performed. This can be used when an <I>eam/fs</I>
potential is used as part of the <I>hybrid</I> pair style. The NULL values
are used as placeholders for atom types that will be used with other
potentials.
</P>
<P>FS EAM files include more information than the DYNAMO <I>setfl</I> format
files read by <I>eam/alloy</I>, so that the i,j density functionals for all
files read by <I>eam/alloy</I>, in that i,j density functionals for all
pairs of elements are included as needed by the Finnis/Sinclair
formulation of the EAM.
</P>
<P>FS EAM files in the <I>potentials</I> directory of the LAMMPS distribution
have a ".eam.fs" suffix. Ther are formatted as follows:
have an ".eam.fs" suffix. They are formatted as follows:
</P>
<UL><LI>lines 1,2,3 = comments (ignored)
<LI>line 4: Nelements = # of elements in the file
<LI>line 4: Nelements Element1 Element2 ... ElementN
<LI>line 5: Nrho, drho, Nr, dr, cutoff
</UL>
<P>The 5-line header section is identical to an EAM <I>setfl</I> file.
@ -250,17 +276,22 @@ have a ".eam.fs" suffix. Ther are formatted as follows:
each with the following format:
</P>
<UL><LI>line 1 = atomic number, mass, lattice constant, lattice type (e.g. FCC)
<LI>embedding function F (Nrho values)
<LI>density function rho for element I at element 1 (Nr values)
<LI>density function rho for element I at element 2
<LI>embedding function F(rho) (Nrho values)
<LI>density function rho(r) for element I at element 1 (Nr values)
<LI>density function rho(r) for element I at element 2
<LI>...
<LI>density function rho for element I at element Nelement
<LI>density function rho(r) for element I at element Nelement
</UL>
<P>Following the Nelements sections, values for the pair potential phi
arrays are listed in the same manner (r*phi) as in EAM <I>setfl</I> files.
Note that the rho arrays in Finnis/Sinclair can be asymmetric (i,j !=
j,i) so there are Nelements^2 of them listed in the file. But the phi
arrays are still symmetric, so only phi arrays for i >= j are listed.
<P>The units of these quantities in line 1 are the same as for <I>setfl</I>
files. Note that the rho(r) arrays in Finnis/Sinclair can be
asymmetric (i,j != j,i) so there are Nelements^2 of them listed in the
file.
</P>
<P>Following the Nelements sections, Nr values for each pair potential
phi(r) array are listed in the same manner (r*phi, units of
eV-Angstroms) as in EAM <I>setfl</I> files. Note that in Finnis/Sinclair,
the phi(r) arrays are still symmetric, so only phi arrays for i >= j
are listed.
</P>
<HR>

181
doc/pair_style_eam.txt
View File

@ -20,13 +20,13 @@ style = {eam} or {eam/alloy} or {eam/fs} :ul
pair_style eam
pair_coeff * * cuu3
pair_coeff 1*3 1*3 niu3 :pre
pair_coeff 1*3 1*3 niu3.eam :pre
pair_style eam/alloy
pair_coeff * * nialhjea 1 2 1 1 :pre
pair_coeff * * ../potentials/nialhjea.eam.alloy Ni Al Ni Ni :pre
pair_style eam/fs
pair_coeff * * nial.fs 1 2 1 1 :pre
pair_coeff * * nialhjea.eam.fs Ni Al Ni Ni :pre
[Description:]
@ -53,30 +53,32 @@ the "potentials" directory of the LAMMPS distribution.
IMPORTANT NOTE: The {eam} style reads single-element EAM potentials in
the DYNAMO {funcfl} format. Either single element or alloy systems
can be modeled with {funcfl} files and style {eam}. For the alloy
case LAMMPS mixes the single-element potentials to produce alloy
potentials the same way that DYNAMO does. Alternatively, DYNAMO
{setfl} files can be used by LAMMPS to model alloy systems by invoking
the {eam/alloy} style as described below. {Setfl} files require no
mixing since they specify alloy interactions explicitly.
can be modeled using multiple {funcfl} files and style {eam}. For the
alloy case LAMMPS mixes the single-element potentials to produce alloy
potentials, the same way that DYNAMO does. Alternatively, a single
DYNAMO {setfl} file of Finnis/Sinclair EAM file can be used by LAMMPS
to model alloy systems by invoking the {eam/alloy} or {eam/fs} styles
as described below. These files require no mixing since they specify
alloy interactions explicitly.
For style {eam}, potential values are read from a file that is in the
DYNAMO single-element {funcfl} format. If the DYNAMO file was created
by a Fortran program, it cannot have "D" values in it for exponents.
C only recognizes "e" or "E" for scientific notation.
Note that unlike for other potentials, you do not set cutoffs for EAM
potentials in the pair_style or pair_coeff command; they are specified
in the EAM potential files.
Note that unlike for other potentials, cutoffs for EAM potentials are
not set in the pair_style or pair_coeff command; they are specified in
the EAM potential files themselves.
For style {eam} you must assign a potential file to each I,I pair of
atom types by using a single pair_coeff argument:
For style {eam} a potential file must be assigned to each I,I pair of
atom types by using one or more pair_coeff commands, each with a
single argument:
filename :ul
Thus the following command
pair_coeff *2 1*2 cuu3 :pre
pair_coeff *2 1*2 cuu3.eam :pre
will read the cuu3 potential file and use the tabulated Cu values for
F, phi, rho that it contains for type pairs 1,1 and 2,2 (type pairs
@ -96,23 +98,35 @@ line 2: atomic number, mass, lattice constant, lattice type (e.g. FCC)
line 3: Nrho, drho, Nr, dr, cutoff :ul
On line 2, all values but the mass are ignored by LAMMPS. The mass is
in atomic mass units which is converted by LAMMPS to the appropriate
internal mass "units"_units.html. On line 3, Nrho and Nr are the
number of tabulated values in the subsequent arrays, drho and dr are
the spacing in density and distance space for the values in those
arrays, and the specified cutoff becomes the pairwise cutoff used by
LAMMPS for the potential. The units of dr are Angstroms; I'm not sure
of the units for drho - some measure of electron density.
in atomic mass units (g/cm^3) which is converted by LAMMPS to the
appropriate internal mass "units"_units.html. The cubic lattice
constant is in Angstroms. On line 3, Nrho and Nr are the number of
tabulated values in the subsequent arrays, drho and dr are the spacing
in density and distance space for the values in those arrays, and the
specified cutoff becomes the pairwise cutoff used by LAMMPS for the
potential. The units of dr are Angstroms; I'm not sure of the units
for drho - some measure of electron density.
Following the 3 header lines are 3 arrays of tabulated values:
embedding function F (Nrho values)
pair potential function phi (Nr values)
density function rho (Nr values) :ul
embedding function F(rho) (Nrho values)
effective charge function Z(r) (Nr values)
density function rho(r) (Nr values) :ul
The values for each array can be listed as multiple values per line,
so long as each array starts on a new line. The individual values are
(for example) phi(r) for r = 0,dr,2*dr, ... (Nr-1)*dr.
so long as each array starts on a new line. For example, the
individual Z(r) values are for r = 0,dr,2*dr, ... (Nr-1)*dr.
The units for the embedding function F are eV. The units for the
density function rho are the same as for drho (see above, electron
density). The units for the effective charge Z are "atomic charge" or
sqrt(Hartree * Bohr-radii). For 2 interacting atoms i,j this is used
by LAMMPS to compute the pair potential term in the EAM energy
expression as r*phi, in units of eV-Angstroms, via the formula
r*phi = 27.2 * 0.529 * Zi * Zj :pre
where 1 Hartree = 27.2 eV and 1 Bohr = 0.529 Angstroms.
:line
@ -126,64 +140,76 @@ interactions. Thus they allow more generality than {funcfl} files for
modeling alloys.
For style {eam/alloy}, potential values are read from a file that is
in the DYNAMO multi-element {setfl} format. If the DYNAMO file was
created by a Fortran program, it cannot have "D" values in it for
exponents. C only recognizes "e" or "E" for scientific notation.
in the DYNAMO multi-element {setfl} format, except that element names
(Ni, Cu, etc) are added to one of the lines in the file. If the
DYNAMO file was created by a Fortran program, it cannot have "D"
values in it for exponents. C only recognizes "e" or "E" for
scientific notation.
Only one pair_coeff command can be used (one file). DYNAMO {setfl}
files contain information for M elements. These are mapped to LAMMPS
atom types by specifying N additional arguments after the filename,
where N is the number of LAMMPS atom types:
Only one pair_coeff command can be used which specifies a single
{setfl} file. DYNAMO {setfl} files contain information for M
elements. These are mapped to LAMMPS atom types by specifying N
additional arguments after the filename, where N is the number of
LAMMPS atom types:
filename
N values from 0 to M = mapping of {setfl} elements to atom types :ul
N element names = mapping of {setfl} elements to atom types :ul
As an example, the nialhjea {setfl} file has tabulated EAM values for
3 elements and their alloy interactions: Ni, Al, and H. If your
LAMMPS simulation has 4 atoms types and you want the 1st 3 to be Ni,
LAMMPS simulation had 4 atoms types and you wanted the 1st 3 to be Ni,
and the 4th to be Al, you would use the following pair_coeff command:
pair_coeff * * nialhjea 1 1 1 2 :pre
pair_coeff * * nialhjea.eam.alloy Ni Ni Ni Al :pre
The 1st 2 arguments must be * * so as to span all LAMMPS atom types.
The first three "1" values map LAMMPS atom types 1,2,3 to the 1st
element (Ni) in the {setfl} file. The final "2" value maps LAMMPS
atom type 4 to the 2nd element = Al. If a mapping value is "0", the
mapping is not performed. This can be used when an {eam/alloy}
potential is used as part of the {hybrid} pair style. The 0 values
are used as placeholders for atom types that will be used with other
potentials.
The first three Ni arguments map LAMMPS atom types 1,2,3 to the Ni
element in the {setfl} file. The final Al argument maps LAMMPS atom
type 4 to the Al element in the {setfl} file. If a mapping value is
specified as NULL, the mapping is not performed. This can be used
when an {eam/alloy} potential is used as part of the {hybrid} pair
style. The NULL values are placeholders for atom types that will be
used with other potentials.
{Setfl} files in the {potentials} directory of the LAMMPS distribution
have a ".eam.alloy" suffix. A DYNAMO multi-element {setfl} file is
formatted as follows:
lines 1,2,3 = comments (ignored)
line 4: Nelements = # of elements in the file
line 4: Nelements Element1 Element2 ... ElementN
line 5: Nrho, drho, Nr, dr, cutoff :ul
The meaning of the values in line 5 is the same as for the {funcfl}
file described above. Note that the cutoff is a global value, valid
for all pairwise interactions for all element pairings.
In a DYNAMO {setfl} file, line 4 only lists Nelements = the # of
elements in the {setfl} file. For LAMMPS, the element name (Ni, Cu,
etc) of each element must be added to the line, in the order the
elements appear in the file.
The meaning and units of the values in line 5 is the same as for the
{funcfl} file described above. Note that the cutoff (in Angstroms) is
a global value, valid for all pairwise interactions for all element
pairings.
Following the 5 header lines are Nelements sections, one for each
element, each with the following format:
line 1 = atomic number, mass, lattice constant, lattice type (e.g. FCC)
embedding function F (Nrho values)
density function rho (Nr values) :ul
embedding function F(rho) (Nrho values)
density function rho(r) (Nr values) :ul
As with the {funcfl} files, only the mass is used by LAMMPS from the 1st
line. The F and rho arrays are unique to a single element and are
formatted the same as in a {funcfl} file.
As with the {funcfl} files, only the mass (g/cm^3) is used by LAMMPS
from the 1st line. The cubic lattice constant is in Angstroms. The F
and rho arrays are unique to a single element and have the same format
and units as in a {funcfl} file.
Following the Nelements sections, values for the pair potential phi
arrays are listed for all i,j element pairs in the same format as
other arrays. Since these interactions are symmetric (i,j = j,i) only
phi arrays with i >= j are listed, in the following order: i,j =
Following the Nelements sections, Nr values for each pair potential
phi(r) array are listed for all i,j element pairs in the same format
as other arrays. Since these interactions are symmetric (i,j = j,i)
only phi arrays with i >= j are listed, in the following order: i,j =
(1,1), (2,1), (2,2), (3,1), (3,2), (3,3), (4,1), ..., (Nelements,
Nelements). The tabulated values for each phi function are listed in
{setfl} files as r*phi, rather than as phi (in {funcfl} files).
Nelements). Unlike the effective charge array Z(r) in {funcfl} files,
the tabulated values for each phi function are listed in {setfl} files
directly as r*phi (in units of eV-Angstroms), since they are for atom
pairs.
:line
@ -211,32 +237,32 @@ potential is the same author's Fe-P FS potential
"(Ackland2)"_#Ackland2. Note that while FS potentials always specify
the embedding energy with a square root dependence on the total
density, the implementation in LAMMPS does not require that; the user
can tabulate any functional form he desires in the FS potential files.
can tabulate any functional form desired in the FS potential files.
For style {eam/fs}, the form of the pair_coeff command is exactly the
same as for style {eam/alloy}, e.g.
pair_coeff * * filename 1 1 1 2 :pre
pair_coeff * * nialhjea.eam.fs Ni Ni Ni Al :pre
where there are N additional arguments after the filename, where N is
the number of LAMMPS atom types. The N values determine the mapping
of LAMMPS atom types to EAM elements in the file, as described above
for style {eam/alloy}. As with {eam/alloy}, if a mapping value is
"0", the mapping is not performed. This can be used when an {eam/fs}
potential is used as part of the {hybrid} pair style. The 0 values
NULL, the mapping is not performed. This can be used when an {eam/fs}
potential is used as part of the {hybrid} pair style. The NULL values
are used as placeholders for atom types that will be used with other
potentials.
FS EAM files include more information than the DYNAMO {setfl} format
files read by {eam/alloy}, so that the i,j density functionals for all
files read by {eam/alloy}, in that i,j density functionals for all
pairs of elements are included as needed by the Finnis/Sinclair
formulation of the EAM.
FS EAM files in the {potentials} directory of the LAMMPS distribution
have a ".eam.fs" suffix. Ther are formatted as follows:
have an ".eam.fs" suffix. They are formatted as follows:
lines 1,2,3 = comments (ignored)
line 4: Nelements = # of elements in the file
line 4: Nelements Element1 Element2 ... ElementN
line 5: Nrho, drho, Nr, dr, cutoff :ul
The 5-line header section is identical to an EAM {setfl} file.
@ -245,17 +271,22 @@ Following the header are Nelements sections, one for each element I,
each with the following format:
line 1 = atomic number, mass, lattice constant, lattice type (e.g. FCC)
embedding function F (Nrho values)
density function rho for element I at element 1 (Nr values)
density function rho for element I at element 2
embedding function F(rho) (Nrho values)
density function rho(r) for element I at element 1 (Nr values)
density function rho(r) for element I at element 2
...
density function rho for element I at element Nelement :ul
density function rho(r) for element I at element Nelement :ul
Following the Nelements sections, values for the pair potential phi
arrays are listed in the same manner (r*phi) as in EAM {setfl} files.
Note that the rho arrays in Finnis/Sinclair can be asymmetric (i,j !=
j,i) so there are Nelements^2 of them listed in the file. But the phi
arrays are still symmetric, so only phi arrays for i >= j are listed.
The units of these quantities in line 1 are the same as for {setfl}
files. Note that the rho(r) arrays in Finnis/Sinclair can be
asymmetric (i,j != j,i) so there are Nelements^2 of them listed in the
file.
Following the Nelements sections, Nr values for each pair potential
phi(r) array are listed in the same manner (r*phi, units of
eV-Angstroms) as in EAM {setfl} files. Note that in Finnis/Sinclair,
the phi(r) arrays are still symmetric, so only phi arrays for i >= j
are listed.
:line