Commit JT 021518

doc/src/pair_spin_soc_neel.txt

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+"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
+
+:link(lws,http://lammps.sandia.gov)
+:link(ld,Manual.html)
+:link(lc,Section_commands.html#comm)
+
+:line
+
+pair_style pair/spin/soc/neel command :h3
+
+[Syntax:]
+
+pair_style pair/spin/soc/neel cutoff :pre
+
+cutoff = global cutoff pair (distance in metal units) :ulb,l
+
+:ule
+	
+[Examples:]
+
+pair_style pair/spin/soc/neel 4.0
+pair_coeff * * neel 4.0 0.0048 0.234 1.168 2.6905 0.705 0.652
+pair_coeff 1 2 neel 4.0 0.0048 0.234 1.168 0.0 0.0 1.0 :pre
+
+[Description:]
+
+Styles {pair/spin/soc} compute pair interactions arising from the spin-orbit 
+coupling (soc). 
+
+Style {pair/spin/soc/neel} computes the Neel pair anisotropy model 
+between pairs of magnetic spins: 
+
+:c,image(Eqs/pair_spin_soc_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.
+
+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)"_#Tranchida1.
+
+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).
+
+More details about the derivation of these torques/forces are reported in
+"(Tranchida)"_#Tranchida1.
+
+:line
+
+[Restrictions:]
+
+All the {pair/spin} styles are part of the SPIN package. 
+These styles are only enabled if LAMMPS was built with this package, and
+if the atom_style "spin" was declared. 
+See the "Making LAMMPS"_Section_start.html#start_3 section for more info.
+
+[Related commands:]
+
+"atom_style spin"_atom_style.html, "pair_coeff"_pair_coeff.html, 
+"pair_eam"_pair_eam.html,
+
+[Default:] none
+
+:line
+
+:link(Tranchida1)
+[(Tranchida)]https://arxiv.org/abs/1801.10233
+