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Methods of quantum chemistry have been applied to double-charged complexes involving the transition metals Ni(2+), Cu(2+) and Zn(2+) with the aromatic amino acids (AAA) phenylalanine, tyrosine and tryptophan. The effect of hydration on the relative stability and geometry of the individual species studied has been evaluated within the supermolecule approach.(More)
The mechanism of the light-induced spin crossover of the [Fe(bpy)3](2+) complex (bpy=2,2'-bipyridine) has been studied by combining accurate electronic-structure calculations and time-dependent approaches to calculate intersystem-crossing rates. We investigate how the initially excited metal-to-ligand charge transfer (MLCT) singlet state deactivates to the(More)
The treatment of relativity and electron correlation on an equal footing is essential for the computation of systems containing heavy elements. Correlation treatments that are based on four-component Dirac–Hartree–Fock calculations presently provide the most accurate, albeit costly, way of taking relativity into account. The requirement of having two(More)
The geometries and energies of factor Xa inhibitors edoxaban, eribaxaban, fidexaban, darexaban, letaxaban, and the dual factor Xa and thrombin inhibitors tanogitran and SAR107375 in both the gas-phase and aqueous solution were studied using the Becke3LYP/6-31++G(d,p) or Grimme's B97D/6-31++G(d,p) method. The fully optimized conformers of these(More)
We calculate the Heisenberg exchange J in the quasi-2D antiferromagnetic cuprates La 2 CuO 4 , YBa 2 Cu 3 O 6 , Nd 2 CuO 4 and Sr 2 CuO 2 Cl 2. We apply all-electron (MC)SCF and non-orthogonal CI calculations toclusters in a model charge embedding. The (MC)SCF triplet and singlet ground states are well characterized by Cu 2+ (d x 2-y 2) and O 2-. The(More)
The character of the ground and optically excited states was investigated by quantum chemical calculations. We propose a rung ground state with V 3d(1)(xy)-O 2p(1)(y)-V 3d(1)(xy) character, instead of the conventional picture of one unpaired electron shared by 2 V ions. The unpaired electron on O is low-spin coupled to the V d electrons and spin density is(More)
In benzophenone, intersystem crossing occurs efficiently between the S1(nπ*) state and the T1 state of dominant nπ* character, leading to excited triplet states after photoexcitation. The transition mechanism between S1(nπ*) and T1 is still a matter of debate, despite several experimental studies. Quantum mechanical calculations have been performed in order(More)
The key parameters associated to the thermally induced spin crossover process have been calculated for a series of Fe(II) complexes with mono-, bi-, and tridentate ligands. Combination of density functional theory calculations for the geometries and for normal vibrational modes, and highly correlated wave function methods for the energies, allows us to(More)
Magnetic interactions in ladder vanadates are determined with quantum chemical computational schemes using the embedded cluster model approach to represent the material. The available experimental data for calcium vanadate is accurately reproduced and the nature of the interladder interaction is established to be ferromagnetic. An analysis of the main(More)