Kurt V. Mikkelsen

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Singlet molecular oxygen (a(1)Delta(g)) has been produced and optically detected in time-resolved experiments upon nonlinear two-photon excitation of a photosensitizer dissolved in water. For a given sensitizer, specific functional groups that impart water solubility and that give rise to larger two-photon absorption cross sections are, in many cases, not(More)
A classical interaction model for the calculation of molecular polarizabilities has been investigated. The model is described by atomic capacitancies, polarizabilities, and a parameter related to the size of the atom, where one set of parameters has been employed for each element. The model has been parameterized for the elements H, C, N, O, F, and Cl from(More)
The (15)N NMR spectrum of adenine in aqueous solution has been modeled using high-level combined density functional theory/molecular mechanics techniques coupled to a dynamical averaging scheme. The explicit consideration of the three lowest-energy tautomers of adenine-H9, H7 and H3-allows for a well-founded comparison to experimental data. Based on a very(More)
The polarizability and second hyperpolarizability of polyacetylene oligomer chains of increasing size up to C(24)H(26) were investigated by means of the Coulomb-attenuating method (CAM-B3LYP) using response theory. It was found that this long-range corrected density functional removes to large parts the overestimation observed for standard methods and in(More)
We present a study of the blueshift of the n-->pi* electronic transition in formaldehyde in aqueous solution using a combined coupled cluster/molecular mechanics model including mutual polarization effects in the Hamiltonian. In addition, we report ground and excited state dipole moments. Configurations are generated from molecular dynamics simulations with(More)
We present a study of the interaction between a phenol molecule and an aerosol particle. The aerosol particle is represented by a cluster of 128 water molecules. Using a classical approach, we present interaction energy surfaces for different relative distances and for three orientations of phenol relative to the particle. From the energy surfaces we find(More)
This work assesses the binding energies of atmospherically relevant clusters containing H2SO4, H2O, NH3 and (CH3)2NH using density functional theory. The performance of seven DFT functionals (B3LYP, CAM-B3LYP, M06-2X, PW91, LC-PW91, PBE0 and ωB97X-D) is evaluated against high level explicitly correlated coupled cluster methods using a test set of 107(More)
This work assesses different computational strategies for predicting structures and Gibb's free energies of reaction of atmospheric prenucleation clusters. The performance of 22 Density Functional Theory functionals in predicting equilibrium structures of molecules and water prenucleation clusters of atmospheric relevance is evaluated against experimental(More)
The dimethylamino nitro stilbene (DANS) molecule is studied for exploring solvent effects on two-photon absorption using the quantum mechanical/molecular mechanical (QM/MM) response theory approach, where the quantum part is represented by density functional theory. We have explored the role of geometrical change of the chromophore in solution, the(More)