Kurt Lejaeghere, Veronique Van Speybroeck, Guido Van Oost, Stefaan Cottenier
A central issue when predicting properties by means of DFT calculations is an assessment of the error bars on the computed quantities. For this purpose, a thorough investigation is conducted over a large and diverse test set of crystalline solids, containing all ground state elemental crystals (except most lanthanides). For several structural properties the difference between DFT calculations and experimental values is assessed. Trends in these deviations are discussed, and a statistically justified error bar is presented for each of the proposed properties to quantify the predictive power of a DFT result. Additionally, the outcome of a DFT simulation slightly depends on what code is used. To evaluate the agreement between the results of two independent DFT packages, a quality factor Delta is defined. It measures a generalized distance between the equations of state (in units of energy). VASP is found to have a Delta value of 2 meV/atom with respect to WIEN2k, while for GPAW it is 3 meV/atom.
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http://arxiv.org/abs/1204.2733
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