forked from lijiext/lammps
92 lines
2.7 KiB
Plaintext
92 lines
2.7 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Commands_all.html)
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:line
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pair_style spin/dmi command :h3
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[Syntax:]
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pair_style spin/dmi cutoff :pre
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cutoff = global cutoff pair (distance in metal units) :ulb,l
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:ule
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[Examples:]
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pair_style spin/dmi 4.0
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pair_coeff * * dmi 2.6 0.001 1.0 0.0 0.0
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pair_coeff 1 2 dmi 4.0 0.00109 0.0 0.0 1.0 :pre
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[Description:]
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Style {spin/dmi} computes the Dzyaloshinskii-Moriya (DM) interaction
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between pairs of magnetic spins.
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According to the expression reported in "(Rohart)"_#Rohart, one has
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the following DM energy:
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:c,image(Eqs/pair_spin_dmi_interaction.jpg)
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where si and sj are two neighboring magnetic spins of two particles,
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eij = (ri - rj)/|ri-rj| is the unit vector between sites i and j,
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and D is the DM vector defining the intensity (in eV) and the direction
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of the interaction.
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In "(Rohart)"_#Rohart, D is defined as the direction normal to the film oriented
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from the high spin-orbit layer to the magnetic ultra-thin film.
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The application of a spin-lattice Poisson bracket to this energy (as described
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in "(Tranchida)"_#Tranchida5) allows to derive a magnetic torque omega, and a
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mechanical force F (for spin-lattice calculations only) for each magnetic
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particle i:
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:c,image(Eqs/pair_spin_dmi_forces.jpg)
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More details about the derivation of these torques/forces are reported in
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"(Tranchida)"_#Tranchida5.
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For the {spin/dmi} pair style, the following coefficients must be defined for
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each pair of atoms types via the "pair_coeff"_pair_coeff.html command as in
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the examples above, or in the data file or restart files read by the
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"read_data"_read_data.html or "read_restart"_read_restart.html commands, and
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set in the following order:
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rc (distance units)
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|D| (energy units)
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Dx, Dy, Dz (direction of D) :ul
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Note that rc is the radius cutoff of the considered DM interaction, |D| is
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the norm of the DM vector (in eV), and Dx, Dy and Dz define its direction.
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None of those coefficients is optional. If not specified, the {spin/dmi}
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pair style cannot be used.
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:line
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[Restrictions:]
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All the {pair/spin} styles are part of the SPIN package. These styles
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are only enabled if LAMMPS was built with this package, and if the
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atom_style "spin" was declared. See the "Build
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package"_Build_package.html doc page for more info.
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[Related commands:]
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"atom_style spin"_atom_style.html, "pair_coeff"_pair_coeff.html,
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"pair_eam"_pair_eam.html,
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[Default:] none
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:line
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:link(Rohart)
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[(Rohart)] Rohart and Thiaville,
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Physical Review B, 88(18), 184422. (2013).
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:link(Tranchida5)
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[(Tranchida)] Tranchida, Plimpton, Thibaudeau and Thompson,
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Journal of Computational Physics, 372, 406-425, (2018).
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