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+ volume = "43",
+ journal = "Phys. Rev. A",
+ author = "Emilio Artacho and Lorenzo Mil\'ans del Bosch",
+ month = jun,
+ URL = "http://link.aps.org/doi/10.1103/PhysRevA.43.5770",
+ doi = "10.1103/PhysRevA.43.5770",
+ year = "1991",
+ title = "Nonorthogonal basis sets in quantum mechanics:
+ Representations and second quantization",
+ issue = "11",
+ publisher = "American Physical Society",
+ pages = "5770--5777",
+ notes = "non-orthogonal basis set",
+}
+
+@Article{loewdin50,
+ author = "Per-Olov L{\"{o}}wdin",
+ collaboration = "",
+ title = "On the Non-Orthogonality Problem Connected with the
+ Use of Atomic Wave Functions in the Theory of Molecules
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+ publisher = "AIP",
+ year = "1950",
+ journal = "The Journal of Chemical Physics",
+ volume = "18",
+ number = "3",
+ pages = "365--375",
+ URL = "http://link.aip.org/link/?JCP/18/365/1",
+ doi = "10.1063/1.1747632",
+ notes = "non orthogonal basis set",
+}
+
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+ author = "Per-Olov Löwdin",
+ title = "Studies in perturbation theory {XIII}. Treatment of
+ constants of motion in resolvent method, partitioning
+ technique, and perturbation theory",
+ journal = "International Journal of Quantum Chemistry",
+ volume = "2",
+ number = "6",
+ publisher = "John Wiley & Sons, Inc.",
+ ISSN = "1097-461X",
+ URL = "http://dx.doi.org/10.1002/qua.560020612",
+ doi = "10.1002/qua.560020612",
+ pages = "867--931",
+ year = "1968",
+}
+
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+ volume = "16",
+ journal = "Phys. Rev. B",
+ author = "D. J. Chadi",
+ month = oct,
+ URL = "http://link.aps.org/doi/10.1103/PhysRevB.16.3572",
+ doi = "10.1103/PhysRevB.16.3572",
+ year = "1977",
+ title = "Localized-orbital description of wave functions and
+ energy bands in semiconductors",
+ issue = "8",
+ publisher = "American Physical Society",
+ pages = "3572--3578",
+ notes = "localized orbitals",
+}
+
+@Article{slater53,
+ volume = "92",
+ journal = "Phys. Rev.",
+ author = "J. C. Slater",
+ month = nov,
+ URL = "http://link.aps.org/doi/10.1103/PhysRev.92.603",
+ doi = "10.1103/PhysRev.92.603",
+ year = "1953",
+ title = "An Augmented Plane Wave Method for the Periodic
+ Potential Problem",
+ issue = "3",
+ publisher = "American Physical Society",
+ pages = "603--608",
+ notes = "augmented plane wave method",
+}
+
+@Article{phillips59,
+ volume = "116",
+ journal = "Phys. Rev.",
+ author = "James C. Phillips and Leonard Kleinman",
+ month = oct,
+ URL = "http://link.aps.org/doi/10.1103/PhysRev.116.287",
+ doi = "10.1103/PhysRev.116.287",
+ year = "1959",
+ title = "New Method for Calculating Wave Functions in Crystals
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+ issue = "2",
+ publisher = "American Physical Society",
+ pages = "287--294",
+ notes = "pseudo potential",
+}
+
+@Article{gonze91,
+ volume = "44",
+ journal = "Phys. Rev. B",
+ author = "Xavier Gonze and Roland Stumpf and Matthias
+ Scheffler",
+ month = oct,
+ URL = "http://link.aps.org/doi/10.1103/PhysRevB.44.8503",
+ doi = "10.1103/PhysRevB.44.8503",
+ year = "1991",
+ title = "Analysis of separable potentials",
+ issue = "16",
+ publisher = "American Physical Society",
+ pages = "8503--8513",
+}