Methods based on the combination of the usual density functional theory (DFT) codes with the Hubbard models are widely used to investigate the properties of strongly correlated materials. Using first-principle calculations we study the electronic and magnetic properties of 20 halfmetallic magnets performing self-consistent GGA+U calculations using both the atomic-limit (AL) and around-mean-field (AMF) functionals for the double counting term, used to subtract the correlation part from the DFT total energy, and compare these results to the usual generalized-gradientapproximation (GGA) calculations. Overall the use of AMF produces results similar to the GGA calculations. On the other hand the effect of AL is diversified depending on the studied material. In general the AL functional produces a stronger tendency towards magnetism leading in some cases to unphysical electronic and magnetic properties. Thus the choice of the adequate double-counting functional is crucial for the results obtained using the GGA+U method.

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Abstract:In February 2013 Christos Tsirogiannis linked a fragmentary Athenian red-figured cup from the collection formed by Dietrich von Bothmer, former chairman of Greek and Roman Art at New York’s Metropolitan Museum of Art, to a tondo in the Villa Giulia, Rome. The Rome fragment was attributed to the Euaion painter. Bothmer had acquired several fragments attributed to this same painter, and some had been donated to the Metropolitan Museum of Art as well as to the J. Paul Getty Museum. Other fragments from this hand were acquired by the San Antonio Museum of Art and the Princeton University Art Museum. In January 2012 it was announced that some fragments from the Bothmer collection would be returned to Italy, because they fitted vases that had already been repatriated from North American collections. The Euaion painter fragments are considered against the phenomenon of collecting and donating fractured pots.

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