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98
doc/pair_eff.html
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@ -15,31 +15,31 @@
</P>
<P>pair_style eff/cut cutoff limit_eradius pressure_with_evirials ecp type1 element1 type2 element2 ... typeN elementN
</P>
<P>cutoff = global cutoff for Coulombic interactions
limit_eradius = limit electron size (optional)
pressure_with_evirials = include electron virials in system pressure (optional)
type1 ... typeN = lammps atom type
element1 ... element2 = element symbol : ul
</P>
<UL><LI>cutoff = global cutoff for Coulombic interactions
<LI>limit_eradius = limit electron size (optional)
<LI>pressure_with_evirials = include electron virials in system pressure (optional)
<LI>type1 ... typeN = LAMMPS atom type
<LI>element1 ... element2 = element symbol
</UL>
<P><B>Examples:</B>
</P>
<P>pair_style eff/cut 39.7
<PRE>pair_style eff/cut 39.7
pair_style eff/cut 40.0 limit_eradius
pair_style eff/cut 40.0 limit_eradius pressure_with_evirials
pair_style eff/cut 40.0 ecp 1 Si 3 C
pair_coeff * *
pair_coeff 2 2 20.0
pair_coeff 1 s 0.320852 2.283269 0.814857
pair_coeff 3 22.721015 0.728733 1.103199 17.695345 6.693621 : pre
</P>
pair_coeff 3 22.721015 0.728733 1.103199 17.695345 6.693621
</PRE>
<P><B>Description:</B>
</P>
<P>This pair style contains a LAMMPS implementation of the electron Force
Field (eFF) potential currently under development at Caltech, as
described in <A HREF = "#Jaramillo-Botero">(Jaramillo-Botero)</A>. The eFF for Z<6 was
first introduced by <A HREF = "#Su">(Su)</A> in 2007. It has been extended to higher Zs
by using effective core potentials (ECPs) that now cover up to 2nd and 3rd
row p-block elements of the periodic table.
described in <A HREF = "#Jaramillo-Botero">(Jaramillo-Botero)</A>. The eFF for Z<6
was first introduced by <A HREF = "#Su">(Su)</A> in 2007. It has been extended to
higher Zs by using effective core potentials (ECPs) that now cover up
to 2nd and 3rd row p-block elements of the periodic table.
</P>
<P>eFF can be viewed as an approximation to QM wave packet dynamics and
Fermionic molecular dynamics, combining the ability of electronic
@ -164,17 +164,21 @@ or tensor). If set, the computed pressure will include the
electronic radial virial contributions to the total pressure (scalar
and tensor).
</P>
<P>The <I>ecp</I> is used to associate an ECP representation for a particular atom type.
The ECP captures the orbital overlap between a core pseudo particle and valence electrons
within the Pauli repulsion. A list of type:element-symbol pairs may be provided for all
ECP representations, after the "ecp" keyword.
<P>The <I>ecp</I> is used to associate an ECP representation for a particular
atom type. The ECP captures the orbital overlap between a core pseudo
particle and valence electrons within the Pauli repulsion. A list of
type:element-symbol pairs may be provided for all ECP representations,
after the "ecp" keyword.
</P>
<P>IMPORTANT NOTE: Default ECP parameters are provided for C, N, O, Al, and Si.
Users can modify these using the <I>pair_coeff</I> command as exemplified above.
For this, the User must distinguish between two different functional forms supported,
one that captures the orbital overlap assuming the s-type core interacts with an s-like valence electron (s-s)
and another that assumes the interaction is s-p. For systems that exhibit significant p-character (e.g. C, N, O)
the s-p form is recommended. The "s" ECP form requires 3 parameters and the "p" 5 parameters.
<P>IMPORTANT NOTE: Default ECP parameters are provided for C, N, O, Al,
and Si. Users can modify these using the <I>pair_coeff</I> command as
exemplified above. For this, the User must distinguish between two
different functional forms supported, one that captures the orbital
overlap assuming the s-type core interacts with an s-like valence
electron (s-s) and another that assumes the interaction is s-p. For
systems that exhibit significant p-character (e.g. C, N, O) the s-p
form is recommended. The "s" ECP form requires 3 parameters and the
"p" 5 parameters.
</P>
<P>IMPORTANT NOTE: there are two different pressures that can be reported
for eFF when defining this pair_style, one (default) that considers
@ -190,35 +194,39 @@ partitioning changes, the total energy remains similar).
</P>
<HR>
<P>IMPORTANT NOTE: This implemention of eFF gives a reasonably
accurate description for systems containing nuclei from Z = 1-6 in "all electron" representations.
For systems with increasingly non-spherical electrons, Users should use the ECP representations.
ECPs are now supported and validated for most of the 2nd and 3rd row elements of the p-block.
Predefined parameters are provided for C, N, O, Al, and Si. The ECP captures the orbital overlap
between the core and valence electrons (i.e. Pauli repulsion) with one of the functional forms:
<P>IMPORTANT NOTE: This implemention of eFF gives a reasonably accurate
description for systems containing nuclei from Z = 1-6 in "all
electron" representations. For systems with increasingly
non-spherical electrons, Users should use the ECP representations.
ECPs are now supported and validated for most of the 2nd and 3rd row
elements of the p-block. Predefined parameters are provided for C, N,
O, Al, and Si. The ECP captures the orbital overlap between the core
and valence electrons (i.e. Pauli repulsion) with one of the
functional forms:
</P>
<CENTER><IMG SRC = "Eqs/eff_ECP1.jpg">
</CENTER>
<CENTER><IMG SRC = "Eqs/eff_ECP2.jpg">
</CENTER>
<P>Where the 1st form correspond to core interactions with s-type valence electrons
and the 2nd to core interactions with p-type valence electrons.
</P>
<P>The current version adds full support for models with fixed-core and ECP
definitions. to enable larger timesteps (i.e. by avoiding the high
frequency vibrational modes -translational and radial- of the 2 s
electrons), and in the ECP case to reduce the increased orbital complexity in higher Z elements (up to Z<18).
A fixed-core should be defined with
a mass that includes the corresponding nuclear mass plus the 2 s
electrons in atomic mass units (2x5.4857990943e-4), and a radius
equivalent to that of minimized 1s electrons (see examples under
/examples/USER/eff/fixed-core). An pseudo-core should be described
with a mass that includes the corresponding nuclear mass, plus all the
core electrons (i.e no outer shell electrons), and a radius equivalent
to that of a corresponding minimized full-electron system. The charge
for a pseudo-core atom should be given by the number of outer shell
<P>Where the 1st form correspond to core interactions with s-type valence
electrons and the 2nd to core interactions with p-type valence
electrons.
</P>
<P>The current version adds full support for models with fixed-core and
ECP definitions. to enable larger timesteps (i.e. by avoiding the
high frequency vibrational modes -translational and radial- of the 2 s
electrons), and in the ECP case to reduce the increased orbital
complexity in higher Z elements (up to Z<18). A fixed-core should be
defined with a mass that includes the corresponding nuclear mass plus
the 2 s electrons in atomic mass units (2x5.4857990943e-4), and a
radius equivalent to that of minimized 1s electrons (see examples
under /examples/USER/eff/fixed-core). An pseudo-core should be
described with a mass that includes the corresponding nuclear mass,
plus all the core electrons (i.e no outer shell electrons), and a
radius equivalent to that of a corresponding minimized full-electron
system. The charge for a pseudo-core atom should be given by the
number of outer shell electrons.
</P>
<P>In general, eFF excels at computing the properties of materials in
extreme conditions and tracing the system dynamics over multi-picosend
timescales; this is particularly relevant where electron excitations

86
doc/pair_eff.txt
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@ -15,8 +15,8 @@ pair_style eff/cut cutoff limit_eradius pressure_with_evirials ecp type1 element
cutoff = global cutoff for Coulombic interactions
limit_eradius = limit electron size (optional)
pressure_with_evirials = include electron virials in system pressure (optional)
type1 ... typeN = lammps atom type
element1 ... element2 = element symbol : ul
type1 ... typeN = LAMMPS atom type
element1 ... element2 = element symbol :ul
[Examples:]
@ -27,16 +27,16 @@ pair_style eff/cut 40.0 ecp 1 Si 3 C
pair_coeff * *
pair_coeff 2 2 20.0
pair_coeff 1 s 0.320852 2.283269 0.814857
pair_coeff 3 22.721015 0.728733 1.103199 17.695345 6.693621 : pre
pair_coeff 3 22.721015 0.728733 1.103199 17.695345 6.693621 :pre
[Description:]
This pair style contains a LAMMPS implementation of the electron Force
Field (eFF) potential currently under development at Caltech, as
described in "(Jaramillo-Botero)"_#Jaramillo-Botero. The eFF for Z<6 was
first introduced by "(Su)"_#Su in 2007. It has been extended to higher Zs
by using effective core potentials (ECPs) that now cover up to 2nd and 3rd
row p-block elements of the periodic table.
described in "(Jaramillo-Botero)"_#Jaramillo-Botero. The eFF for Z<6
was first introduced by "(Su)"_#Su in 2007. It has been extended to
higher Zs by using effective core potentials (ECPs) that now cover up
to 2nd and 3rd row p-block elements of the periodic table.
eFF can be viewed as an approximation to QM wave packet dynamics and
Fermionic molecular dynamics, combining the ability of electronic
@ -161,17 +161,21 @@ or tensor). If set, the computed pressure will include the
electronic radial virial contributions to the total pressure (scalar
and tensor).
The {ecp} is used to associate an ECP representation for a particular atom type.
The ECP captures the orbital overlap between a core pseudo particle and valence electrons
within the Pauli repulsion. A list of type:element-symbol pairs may be provided for all
ECP representations, after the "ecp" keyword.
The {ecp} is used to associate an ECP representation for a particular
atom type. The ECP captures the orbital overlap between a core pseudo
particle and valence electrons within the Pauli repulsion. A list of
type:element-symbol pairs may be provided for all ECP representations,
after the "ecp" keyword.
IMPORTANT NOTE: Default ECP parameters are provided for C, N, O, Al, and Si.
Users can modify these using the {pair_coeff} command as exemplified above.
For this, the User must distinguish between two different functional forms supported,
one that captures the orbital overlap assuming the s-type core interacts with an s-like valence electron (s-s)
and another that assumes the interaction is s-p. For systems that exhibit significant p-character (e.g. C, N, O)
the s-p form is recommended. The "s" ECP form requires 3 parameters and the "p" 5 parameters.
IMPORTANT NOTE: Default ECP parameters are provided for C, N, O, Al,
and Si. Users can modify these using the {pair_coeff} command as
exemplified above. For this, the User must distinguish between two
different functional forms supported, one that captures the orbital
overlap assuming the s-type core interacts with an s-like valence
electron (s-s) and another that assumes the interaction is s-p. For
systems that exhibit significant p-character (e.g. C, N, O) the s-p
form is recommended. The "s" ECP form requires 3 parameters and the
"p" 5 parameters.
IMPORTANT NOTE: there are two different pressures that can be reported
for eFF when defining this pair_style, one (default) that considers
@ -187,34 +191,38 @@ partitioning changes, the total energy remains similar).
:line
IMPORTANT NOTE: This implemention of eFF gives a reasonably
accurate description for systems containing nuclei from Z = 1-6 in "all electron" representations.
For systems with increasingly non-spherical electrons, Users should use the ECP representations.
ECPs are now supported and validated for most of the 2nd and 3rd row elements of the p-block.
Predefined parameters are provided for C, N, O, Al, and Si. The ECP captures the orbital overlap
between the core and valence electrons (i.e. Pauli repulsion) with one of the functional forms:
IMPORTANT NOTE: This implemention of eFF gives a reasonably accurate
description for systems containing nuclei from Z = 1-6 in "all
electron" representations. For systems with increasingly
non-spherical electrons, Users should use the ECP representations.
ECPs are now supported and validated for most of the 2nd and 3rd row
elements of the p-block. Predefined parameters are provided for C, N,
O, Al, and Si. The ECP captures the orbital overlap between the core
and valence electrons (i.e. Pauli repulsion) with one of the
functional forms:
:c,image(Eqs/eff_ECP1.jpg)
:c,image(Eqs/eff_ECP2.jpg)
Where the 1st form correspond to core interactions with s-type valence electrons
and the 2nd to core interactions with p-type valence electrons.
The current version adds full support for models with fixed-core and ECP
definitions. to enable larger timesteps (i.e. by avoiding the high
frequency vibrational modes -translational and radial- of the 2 s
electrons), and in the ECP case to reduce the increased orbital complexity in higher Z elements (up to Z<18).
A fixed-core should be defined with
a mass that includes the corresponding nuclear mass plus the 2 s
electrons in atomic mass units (2x5.4857990943e-4), and a radius
equivalent to that of minimized 1s electrons (see examples under
/examples/USER/eff/fixed-core). An pseudo-core should be described
with a mass that includes the corresponding nuclear mass, plus all the
core electrons (i.e no outer shell electrons), and a radius equivalent
to that of a corresponding minimized full-electron system. The charge
for a pseudo-core atom should be given by the number of outer shell
Where the 1st form correspond to core interactions with s-type valence
electrons and the 2nd to core interactions with p-type valence
electrons.
The current version adds full support for models with fixed-core and
ECP definitions. to enable larger timesteps (i.e. by avoiding the
high frequency vibrational modes -translational and radial- of the 2 s
electrons), and in the ECP case to reduce the increased orbital
complexity in higher Z elements (up to Z<18). A fixed-core should be
defined with a mass that includes the corresponding nuclear mass plus
the 2 s electrons in atomic mass units (2x5.4857990943e-4), and a
radius equivalent to that of minimized 1s electrons (see examples
under /examples/USER/eff/fixed-core). An pseudo-core should be
described with a mass that includes the corresponding nuclear mass,
plus all the core electrons (i.e no outer shell electrons), and a
radius equivalent to that of a corresponding minimized full-electron
system. The charge for a pseudo-core atom should be given by the
number of outer shell electrons.
In general, eFF excels at computing the properties of materials in
extreme conditions and tracing the system dynamics over multi-picosend
timescales; this is particularly relevant where electron excitations