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howto:xas_tdp [2021/08/02 15:39]
abussy [Simple examples]
howto:xas_tdp [2021/08/02 15:40]
abussy [FAQ]
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 === Why is the LOCALIZE keyword required ? === === Why is the LOCALIZE keyword required ? ===
-In order to efficiently evaluate the antisymmetric integrals of the type $\langle Ia | jk \rangle$, the same local RI scheme as XAS_TDP is used. Therefore, the core state $I$ needs to be local in space. However, the rotation required to get the pseudocanonical orbitals needed for the original GW2X scheme may break this localization, provided that there are other equivalent atoms in the system. To prevent that from happening, all core states localized on other atoms are ignored for the rotation and the subsequent IP calculation. This has negligible impact since core states belonging to different atoms only weakly interact. It is however important to keep the value of the LOCALIZE keyword to a minimum to insure that only core states are ignored.+In order to efficiently evaluate the antisymmetric integrals of the type $\langle Ia || jk \rangle$, the same local RI scheme as XAS_TDP is used. Therefore, the core state $I$ needs to be local in space. However, the rotation required to get the pseudocanonical orbitals needed for the original GW2X scheme may break this localization, provided that there are other equivalent atoms in the system. To prevent that from happening, all core states localized on other atoms are ignored for the rotation and the subsequent IP calculation. This has negligible impact since core states belonging to different atoms only weakly interact. It is however important to keep the value of the LOCALIZE keyword to a minimum to insure that only core states are ignored.
howto/xas_tdp.txt ยท Last modified: 2021/08/16 14:48 by abussy