pair_style spin/magelec command

Syntax

pair_style spin/magelec cutoff

cutoff = global cutoff pair (distance in metal units)

Examples

pair_style spin/magelec 4.5
pair_coeff * * magelec 4.5 0.00109 1.0 1.0 1.0

Description

Style spin/me computes a magneto-electric interaction between pairs of magnetic spins. According to the derivation reported in (Katsura), this interaction is defined as:

\begin{aligned} {\vec{ω}}_{i} & = - \frac{1}{ℏ} \sum_{j}^{N e i g h b} {\vec{s}}_{j} \times \vec{D} (r_{i j}) \\ {\vec{F}}_{i} & = - \sum_{j}^{N e i g h b} \frac{\partial D (r_{i j})}{\partial r_{i j}} ({\vec{s}}_{i} \times {\vec{s}}_{j}) \cdot {\vec{r}}_{i j} \end{aligned}

where ${\vec{s}}_{i}$ and ${\vec{s}}_{j}$ are neighboring magnetic spins of two particles.

From this magneto-electric interaction, each spin i will be submitted to a magnetic torque omega, and its associated atom can be submitted to a force F for spin-lattice calculations (see fix nve/spin), such as:

\begin{aligned} {\vec{F}}^{i} & = - \sum_{j}^{N e i g h b o r} ({\vec{s}}_{i} \times {\vec{s}}_{j}) \times \vec{E} \\ {\vec{ω}}^{i} = - \frac{1}{ℏ} \sum_{j}^{N e i g h b o r} {\vec{s}}_{j} \times (\vec{E} \times r_{i j}) \end{aligned}

with h the Planck constant (in metal units) and $\vec{E}$ 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).

More details about the derivation of these torques/forces are reported in (Tranchida).

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 Build package page for more info.

Default

none

(Katsura) H. Katsura, N. Nagaosa, A.V. Balatsky. Phys. Rev. Lett., 95(5), 057205. (2005)

(Tranchida) Tranchida, Plimpton, Thibaudeau, and Thompson, Journal of Computational Physics, 372, 406-425, (2018).