Sketch of the chemical structures. (Top) model donor/acceptor compounds in the Cartesian frame; (bottom) molecular switches where the red arrows represent the long or charge-transfer axis of the molecule. For the P n species, labels are given for those geometrical parameters that enter into the definition of the bond length alternations.
SiO2 supercell (left), magnification (center), and its functionalization (right).
Potential energy curve along the interring dihedral coordinate of T 2.
β values as a function of the linker size calculated at the DFTB, HF, MP2, B3LYP, and PBE levels. Lines are guidelines for the eyes.
Model donor/acceptor molecules (top) and their β values sorted as a function of increasing amplitudes at the MP2 level (bottom).
Conventions for the spherical coordinates used in the β mapping.
Static β maps as a function of the ϕ and θ angles. (Top) DFTB calculation, (bottom) model from Eq. (11) .
Representative optimized bond lengths for molecules AE 4 and AY 4 (Å). ⟨BLA⟩ is the average BLA considering all pairs of consecutive single/double or single/triple CC bonds.
Selected optimized geometrical parameters for P 2 and T 2 (distances in Å, angles in °). The ⟨BLA⟩’s are average bond length alternations characterizing the CC π-conjugated pathway between the donor and the acceptor. Two types of BLAs are distinguished as a function of the types of bonds, BLA intra = b− or f− and BLA inter = d− where the bond length labels are defined in Figure 1 .
Molecular electrical properties (in a.u.) for the AE n and AY n molecules with 4 and 6 units linkers. All first principles calculations employed the 6-311G* * basis set, except CCSD(T) using the 6-31G* basis set.
First hyperpolarizability values (in a.u.) for the P n and T n molecules with 2 to 6 units linkers.
First hyperpolarizability values (in a.u.) of the OF and CF of the indolino-oxazolidine compound calculated at the SCC-DFTB level for different electric field directions with respect to the molecular frame (see Figure S1 of the supplementary material for the definition of these directions).
Electrical properties of the isolated/adsorbed molecular switch at the SCC-DFTB level, with the electric field oriented along the C–O/Si direction for the isolated compounds, and along the z direction for the adsorbed ones [a.u.].
First hyperpolarizability values of the different fragments of the functionalized SiO2 surface, and comparison with the whole system [a.u.].
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