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Commit f2a6aa24 authored by julient31's avatar julient31
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Commit2 JT 052918: doc

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doc/src/Eqs/pair_spin_dmi_interaction.jpg

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doc/src/Eqs/pair_spin_dmi_interaction.jpg

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doc/src/Eqs/pair_spin_dmi_interaction.jpg
doc/src/Eqs/pair_spin_dmi_interaction.jpg
doc/src/Eqs/pair_spin_dmi_interaction.jpg
doc/src/Eqs/pair_spin_dmi_interaction.jpg
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......@@ -5,7 +5,12 @@
\begin{document}
\begin{varwidth}{50in}
\begin{equation}
\bm{H}_{dm} = \sum_{{ i,j}=1,i\neq j}^{N} \vec{D}\left(r_{ij}\right) \cdot\left(\vec{s}_{i}\times \vec{s}_{j}\right), \nonumber
\bm{H}_{dm} = -\sum_{{ i,j}=1,i\neq j}^{N}
\left( \vec{e}_{ij} \times \vec{D} \right)
\cdot\left(\vec{s}_{i}\times \vec{s}_{j}\right),
\nonumber
\end{equation}
\end{varwidth}
\end{document}
\vec{D}\left(r_{ij}\right)
{\rm ~and~} \vec{D}\left(r_{ij}\right) = \vec{e}_{ij} \times \vec{D}
doc/src/Eqs/pair_spin_me_interaction.jpg

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doc/src/Eqs/pair_spin_me_interaction.jpg

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doc/src/Eqs/pair_spin_me_interaction.jpg
doc/src/Eqs/pair_spin_me_interaction.jpg
doc/src/Eqs/pair_spin_me_interaction.jpg
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doc/src/Eqs/pair_spin_neel_functions.jpg

5.8 KiB

\documentclass[preview]{standalone}
\usepackage{varwidth}
\usepackage[utf8x]{inputenc}
\usepackage{amsmath,amssymb,amsthm,bm}
\begin{document}
\begin{varwidth}{50in}
\begin{eqnarray}
g_1(r_{ij}) &=& g(r_{ij}) + \frac{12}{35} q(r_{ij}) \nonumber \\
q_1(r_{ij}) &=& \frac{9}{5} q(r_{ij}) \nonumber \\
q_2(r_{ij}) &=& - \frac{2}{5} q(r_{ij}) \nonumber
\end{eqnarray}
\end{varwidth}
\end{document}
doc/src/Eqs/pair_spin_neel_interaction.jpg

10.8 KiB

\documentclass[preview]{standalone}
\usepackage{varwidth}
\usepackage[utf8x]{inputenc}
\usepackage{amsmath,amssymb,amsthm,bm}
\begin{document}
\begin{varwidth}{50in}
\begin{equation}
\mathcal{H}_{N\acute{e}el}=-\sum_{{ i,j=1,i\neq j}}^N g_1(r_{ij})\left(({\bm e}_{ij}\cdot {\bm s}_{i})({\bm e}_{ij}
\cdot {\bm s}_{j})-\frac{{\bm s}_{i}\cdot{\bm s}_{j}}{3} \right)
+q_1(r_{ij})\left( ({\bm e}_{ij}\cdot {\bm s}_{i})^2 -\frac{{\bm s}_{i}\cdot{\bm s}_{j}}{3}\right)
\left( ({\bm e}_{ij}\cdot {\bm s}_{i})^2 -\frac{{\bm s}_{i}\cdot{\bm s}_{j}}{3} \right)
+ q_2(r_{ij}) \Big( ({\bm e}_{ij}\cdot {\bm s}_{i}) ({\bm e}_{ij}\cdot {\bm s}_{j})^3 + ({\bm e}_{ij}\cdot
{\bm s}_{j}) ({\bm e}_{ij}\cdot {\bm s}_{i})^3\Big) \nonumber
\end{equation}
\end{varwidth}
\end{document}
......@@ -21,7 +21,7 @@ compute out_mag all compute/spin :pre
[Description:]
Define a computation that calculates the magnetic quantities for a system
Define a computation that calculates magnetic quantities for a system
of atoms having spins.
This compute calculates 6 magnetic quantities.
......@@ -30,11 +30,11 @@ The three first quantities are the x,y and z coordinates of the total magnetizat
The fourth quantity is the norm of the total magnetization.
The fifth one is referred to as the spin temperature, according
The fifth quantity is the magnetic energy.
The sixth one is referred to as the spin temperature, according
to the work of "(Nurdin)"_#Nurdin1.
The sixth quantity is the magnetic energy.
The simplest way to output the results of the compute spin calculation
is to define some of the quantities as variables, and to use the thermo and
thermo_style commands, for example:
......
......@@ -44,15 +44,16 @@ in metal units).
More details about this implementation are reported in "(Tranchida)"_#Tranchida2.
Note: due to the form of the sLLG equation, this fix has to be the last defined
magnetic fix before the integration/spin fix. As an example:
Note: due to the form of the sLLG equation, this fix has to be defined just
before the nve/spin fix (and after all other magnetic fixes).
As an example:
fix 1 all force/spin zeeman 0.01 0.0 0.0 1.0
fix 2 all langevin/spin 300.0 0.01 21
fix 3 all integration/spin lattice yes :pre
is correct, but defining a force/spin command after the langevin/spin command
would send an error message.
would give an error message.
Note: The random # {seed} must be a positive integer. A Marsaglia random
number generator is used. Each processor uses the input seed to
......@@ -79,7 +80,7 @@ The {langevin/spin} fix is part of the SPIN package.
This style is only enabled if LAMMPS was built with this package.
See the "Making LAMMPS"_Section_start.html#start_3 section for more info.
The numerical integration has to be performed with {fix/integration/spin}
The numerical integration has to be performed with {fix/nve/spin}
when {langevin/spin} is enabled.
This fix has to be the last defined magnetic fix before the integration fix
......
......@@ -39,7 +39,7 @@ the equations of motion of the spin lattice system, following the scheme:
according to the implementation reported in "(Omelyan)"_#Omelyan1.
A sectoring enables this scheme for parallel calculations.
A sectoring method enables this scheme for parallel calculations.
The implementation of this sectoring algorithm is reported
in "(Tranchida)"_#Tranchida1.
......
......@@ -30,31 +30,15 @@ between pairs of magnetic spins:
:c,image(Eqs/pair_spin_dmi_interaction.jpg)
where si and sj are two neighboring magnetic spins of two particles,
rij = ri - rj is the inter-atomic distance between the two particles,
and D(rij) is the DM vector defining the intensity and the
sign of the exchange interaction.
eij = (ri - rj)/|ri-rj| is the normalized separation vector between the
two particles, and D is the DM vector defining the intensity and the
sign of the interaction.
This function is defined as:
:c,image(Eqs/pair_spin_exchange_function.jpg)
where a, b and d are the three constant coefficients defined in the associated
"pair_coeff" command.
The coefficients a, b, and d need to be fitted so that the function above matches with
the value of the DM interaction for the N neighbor shells taken
into account.
Examples and more explanations about this function and its parametrization are reported
in "(Tranchida)"_#Tranchida5.
Examples and more explanations about this interaction and its parametrization are
reported in "(Tranchida)"_#Tranchida5.
From this DM interaction, each spin i will be submitted to a magnetic torque
omega and its associated atom to a force F (for spin-lattice calculations only),
such as:
:c,image(Eqs/pair_spin_soc_dmi_forces.jpg)
with h the Planck constant (in metal units).
omega and its associated atom to a force F (for spin-lattice calculations only).
More details about the derivation of these torques/forces are reported in
"(Tranchida)"_#Tranchida5.
......
......@@ -30,7 +30,7 @@ pairs of magnetic spins. According to the derivation reported in
:c,image(Eqs/pair_spin_me_interaction.jpg)
where si and sj are neighboring magnetic spins of two particles,
rij = ri - rj is the normalized separation vector between the
eij = (ri - rj)/|ri-rj| is the normalized separation vector between the
two particles, and E is an electric polarization vector.
The norm and direction of E are giving the intensity and the
direction of a screened dielectric atomic polarization (in eV).
......
......@@ -27,14 +27,18 @@ pair_coeff 1 2 neel 4.0 0.0048 0.234 1.168 0.0 0.0 1.0 :pre
Style {spin/neel} computes the Neel pair anisotropy model
between pairs of magnetic spins:
:c,image(Eqs/pair_spin_dmi_interaction.jpg)
:c,image(Eqs/pair_spin_neel_interaction.jpg)
where si and sj are two neighboring magnetic spins of two particles,
rij = ri - rj is the inter-atomic distance between the two particles,
and D(rij) is the DM vector defining the intensity and the
sign of the exchange interaction.
eij = (ri - rj)/|ri-rj| is their normalized separation vector
and g1, q1 and q2 are three functions defining the intensity of the
dipolar and quadrupolar contributions, with:
This function is defined as:
:c,image(Eqs/pair_spin_neel_functions.jpg)
With the functions g(rij) and q(rij) defined and fitted according to the same
Bethe-Slater function used to fit the exchange interaction:
:c,image(Eqs/pair_spin_exchange_function.jpg)
......@@ -42,19 +46,14 @@ where a, b and d are the three constant coefficients defined in the associated
"pair_coeff" command.
The coefficients a, b, and d need to be fitted so that the function above matches with
the value of the DM interaction for the N neighbor shells taken
into account.
the values of the magneto-elastic constant of the materials at stake.
Examples and more explanations about this function and its parametrization are reported
in "(Tranchida)"_#Tranchida6.
in "(Tranchida)"_#Tranchida6. More examples of parametrization will be provided in
future work.
From this DM interaction, each spin i will be submitted to a magnetic torque
omega and its associated atom to a force F (for spin-lattice calculations only),
such as:
:c,image(Eqs/pair_spin_soc_dmi_forces.jpg)
with h the Planck constant (in metal units).
omega and its associated atom to a force F (for spin-lattice calculations only).
More details about the derivation of these torques/forces are reported in
"(Tranchida)"_#Tranchida6.
......
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