Exchange-correlation errors at harmonic and anharmonic orders: the case of bulk Cu |
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Authors: | Shobhana Narasimhan Stefano De Gironcoli |
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Affiliation: | (1) Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur PO, 560 064 Bangalore, India;(2) Istituto Nazionale per la Fisica della Materia, Scuola Internazionale Superiore di Studi Avanzati, Via Beirut 2–4, I-34014 Trieste, Italy |
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Abstract: | As an aid towards improving the treatment of exchange and correlation effects in electronic structure calculations, it is desirable to have a clear picture of the errors introduced by currently popular approximate exchange-correlation functionals. We have performed ab initio density functional theory and density functional perturbation theory calculations to investigate the thermal properties of bulk Cu, using both the local density approximation (LDA) and the generalized gradient approximation (GGA). Thermal effects are treated within the quasiharmonic approximation. We find that the LDA and GGA errors for anharmonic quantities are an order of magnitude smaller than for harmonic quantities; we argue that this might be a general feature. We also obtain much closer agreement with experiment than earlier, more approximate calculations. |
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Keywords: | Anharmonicity density functional theory exchange correlation copper |
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