IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Magnetic models from ab-initio simulations
Autor/es:
C. A LAMAS
Lugar:
La Plata
Reunión:
Workshop; VIII Workshop on Novel Methods for Electronic Structure CalculationsIntroduction to Com- putational Modeling Methods in Materials Science; 2019
Resumen:
The theoretical prediction of the phases present in magnetic materials is a major problem in condensedmatter physics. Due to the quantum nature of magnetism, an exact description would inprinciple require solving the Schr¨odinger equation for a system of many electrons, which is computationallyintractable. While first principles calculations provide a very powerful tool to approximateproperties such as base energies and electron densities, they are intrinsically incapable of predictingthe complex superpositions of spin states on the magnetic atoms found in frustrated magnetic systems.On the other hand, the use of effective models of localized spins, for which it is possible to treatthese superpositions of states, requires as input a set of coupling constants that grows with the complexityof the system that is to be represented. The usual strategy for determining these constantsis to compare the energies predicted by the calculation of first principles with that of the effectivemodel, on a set of spin configurations, to define a system of linear constraints (overdetermined) onthe coupling constants. Due to the huge number of possible spin configurations, in general, it is onlypossible to determine a small number of these restrictions.In this talk, I will discuss some ideas on how to efficiently choose the set of spin configurationsto guarantee the stability of the system of equations, and a method for - once these restrictions areknown - determine the confidence interval around the estimated values of the coupling constants.Finally, I will present a piece of software that allows for automatizing these tasks.