(a) Ca2+–Atrazine model at the equilibrium geometry. (b) Two zones are defined: zone 1 in bold (Th = 0.0001 a.u.) and zone 2 in watermark (various thresholds are used).
Atrazine–Ca2+ elongation (Ångströms). Comparison of selected CI with vs without zones. Relative error to the SDCI values.
Atrazine–Ca2+ elongation (Ångströms). Interzone thresholds. Relative error to the SDCI values.
Atrazine–Ca2+ elongation (Ångströms) with transfer of the topological matrix. Relative error to the SDCI values.
Schematic view of the axial approach of a hydrogen molecule to a (0,9) nanotube fragment.
H2 approach to a nanotube fragment: σ and σ * localized orbitals.
Surface of the nanotube. Kékulé π orbitals, and atom centered π and π * orbitals as they are used in the localisation procedure.
H2 approach to a nanotube fragment: π and π * localized orbitals.
H2 approach to a nanotube fragment. Taking account of the σ skeleton through variation of thresholds. Since the total energies obtained are different in the various cases, all energies are set to zero at 15 Angströms, in order to see the deviation from the reference curve.
H2 approach to a nanotube fragment. Taking account of the “diffuse” functions through variation of thresholds.
[Cu4(hpda)4][ClO4] H2O with hpda = N-(2-hydroxyethyl)-1,3-propane-diamine molecule. Pink, red, blue, gray, and white balls represent Cu, O, N, C, and H atoms, respectively.
Ca2+–Atrazine model. Dimensions of the calculations with and without partition into zones as a function of integral exchange thresholds (a.u.). Average thresholds are used between the two zones.
Ca2+–Atrazine model. Dimensions of the calculations as a function of the interzone threshold options (a.u.).
Ca2+–Atrazine model. Topological matrix transferred. Maximal error on the potential energy curve compared to standard SDCI as a function of exchange integral thresholds (a.u.) with and without zones.
H2 approach to a nanotube. Dimensions of the calculations as a function of Th 1 / Th 2 / Th i (a.u.) thresholds. For zone 1 (π, H2), the same thresholds were used for all calculations: Th 1 = 0.002 a.u., Th 2 = 0.001 a.u., and Th i = 0.0001 a.u.
H2 approach to a nanotube. Position of the extrema (Å) as a function of the thresholds of the zone 3 (σ skeleton).
H2 approach to a nanotube. Interaction energy at the extrema (kcal mol–1)) as a function of the thresholds of the zone 3 (σ skeleton).
Magnetic coupling terms (in cm−1) for the Cu4O4 cubane obtained from EXSCI calculations with different thresholds, CPU time in minutes per iteration and root, and number of determinants in the CI space. In parenthesis, the corresponding percentage of the DDCI space included in the calculations is shown. The full DDCI space contains 8743 × 106 determinants.
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