RT info:eu-repo/semantics/article
T1 Magnetostatic Dipolar Energy of Large Periodic Ni fcc Nanowires, Slabs and Spheres
A1 Cabria Álvaro, Iván
K1 Nanomagnetism
K1 Nanomagnetismo
K1 Magnetostatic dipolar energy
K1 Energía dipolar magnetostática
K1 Ewald method
K1 Método de Ewald
AB The computational effort to calculate the magnetostatic dipolar energy, MDE, of a periodic cell of N magnetic momentsis an O(N2) task. Compared with the calculation of the Exchange and Zeeman energy terms, this is the mostcomputationally expensive part of the atomistic simulations of the magnetic properties of large periodic magneticsystems. Two strategies to reduce the computational effort have been studied: An analysis of the traditional Ewaldmethod to calculate the MDE of periodic systems and parallel calculations. The detailed analysis reveals that, for certaintypes of periodic systems, there are many matrix elements of the Ewald method identical to another elements, dueto some symmetry properties of the periodic systems. Computation timing experiments of the MDE of large periodicNi fcc nanowires, slabs and spheres, up to 32000 magnetic moments in the periodic cell, have been carried out andthey show that the number of matrix elements that should be calculated is approximately equal to N, instead of N2/2,if these symmetries are used, and that the computation time decreases in an important amount. The time complexityof the analysis of the symmetries is O(N3), increasing the time complexity of the traditional Ewald method. MDE isa very small energy and therefore, the usual required precision of the calculation of the MDE is so high, about 10−6eV/cell, that the calculations of large periodic magnetic systems are very expensive and the use of the symmetriesreduces, in practical terms, the computation time of the MDE in a significant amount, in spite of the increase of thetime complexity. The second strategy consists on parallel calculations of the MDE without using the symmetries ofthe periodic systems. The parallel calculations have been compared with serial calculations that use the symmetries.
PB Elsevier
SN 0169-4332
YR 2019
FD 2019
LK http://uvadoc.uva.es/handle/10324/36734
UL http://uvadoc.uva.es/handle/10324/36734
LA eng
NO Applied Surface Science, 2019, vol. 490. p. 352-364
NO Producción Científica
DS UVaDOC
RD 29-sep-2022