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Other version: http://link.aip.org/link/JCPSA6/v135/i8/p084120/s1
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Title 
Selfconsistency in frozendensity embedding theory based calculations 

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Published in  Journal of Chemical Physics. 2011, vol. 135, no. 8, p. 084120  
Abstract  The bifunctional for the nonelectrostatic part of the exact embedding potential of frozendensity embedding theory (FDET) depends on whether the embedded part is described by means of a real interacting manyelectron system or the reference system of noninteracting electrons (see [Wesolowski, Phys. Rev. A. 77, 11444 (2008)]). The difference δΔFMD[ρA] / δρA(r), where ΔFMD[ρA] is the functional bound from below by the correlation functional Ec[ρA] and from above by zero. Taking into account ΔFMD[ρA] in both the embedding potential and in energy is indispensable for assuring that all calculated quantities are selfconsistent and that FDET leads to the exact energy and density in the limit of exact functionals. Since not much is known about good approximations for ΔFMD[ρA], we examine numerically the adequacy of neglecting ΔFMD[ρA] entirely. To this end, we analyze the significance of δΔFMD[ρA] / δρA(r) in the case where the magnitude of ΔFMD[ρA] is the largest, i.e., for HartreeFock wavefunction. In hydrogen bonded model systems, neglecting δΔFMD[ρA] / δρ(r) in the embedding potential marginally affects the total energy (less than 5% change in the interaction energy) but results in qualitative changes in the calculated hydrogenbonding induced shifts of the orbital energies. Based on this estimation, we conclude that neglecting δΔFMD[ρA] / δρA(r) may represent a good approximation for multireference variational methods using adequate choice for the active space. Doing the same for singlereference perturbative methods is not recommended. Not only it leads to violation of selfconsistency but might result in large effect on orbital energies. It is shown also that the errors in total energy due to neglecting δΔFMD[ρA] / δρA(r) do not cancel but rather add up to the errors due to approximation for the bifunctional of the nonadditive kinetic potential.  
Identifiers  DOI: 10.1063/1.3624888  
Note  density functional theory, HF calculations, hydrogen bonds, SCF calculations, variational techniques  
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Research group  Groupe Wesolowski  
Citation (ISO format)  AQUILANTE, Francesco, WESOLOWSKI, Tomasz Adam. Selfconsistency in frozendensity embedding theory based calculations. In: Journal of Chemical Physics, 2011, vol. 135, n° 8, p. 084120. https://archiveouverte.unige.ch/unige:16946 