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A new method is presented, which makes it possible to partition molecular properties like multipole moments and polarizabilities, into atomic and interatomic contributions. The method requires a subdivision of the atomic basis set into occupied and virtual basis functions for each atom in the molecular system. The localization procedure is organized into a series of orthogonalizations of the original basis set, which will have as a final result a localized orthonormal basis set. The new localization procedure is demonstrated to be stable with various basis sets, and to provide physically meaningful localized properties. Transferability of the methyl properties for the alkane series and of the carbon and hydrogen properties for the benzene, naphtalene, and anthracene series is demonstrated.

Abstract:The coordination environment of uranyl in water has been studied using a combined quantum mechanical and molecular dynamics approach. Multiconfigurational wave function calculations have been performed to generate pair potentials between uranyl and water. The quantum chemically determined energies have been used to fit parameters in a polarizable force field with an added charge transfer term. Molecular dynamics simulations have been performed for the uranyl ion and up to 400 water molecules. The results show a uranyl ion with five water molecules coordinated in the equatorial plane. The U-O(H 2O) distance is 2.40 Å, which is close to the experimental estimates. A second coordination shell starts at about 4.7 Å from the uranium atom. No hydrogen bonding is found between the uranyl oxygens and water. Exchange of waters between the first and second solvation shell is found to occur through a path intermediate between association and interchange. This is the first fully ab initio determination of the solvation of the uranyl ion in water.

We show that coherent electron transport through zero-dimensional systems can be used to tailor the shape of the system's transmission function. This quantum-engineering approach can be used to enhance the performance of quantum dots or molecules in thermal-to-electric power conversion. Specifically, we show that electron interference in a two-level system can substantially improve the maximum thermoelectric power and the efficiency at maximum power by suppressing parasitic charge flow near the Fermi energy, and by reducing electronic heat conduction. We discuss possible realizations of this approach in molecular junctions or quantum dots.

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4098 4.1. Intermolecular Potentials 4098 4.2. Applications 4098 5. Simulations of Liquids and Solutions 4099 5.1. Liquid Water 4100 5.2. Solvation of Ions in Water 4101 5.3. Aqueous Urea Solutions 4101 5.4. Liquid Formaldehyde 4102 5.5. Liquid Acetonitrile and Solvation of the Sodium Ion in Acetonitrile 4102 6. Intermolecular Potentials for Flexible Molecules 4102 6.1. Inter-and Intramolecular Potentials 4102 6.2. 1,2-Dimethoxyethane in Water Solution 4103 7. Solvent Effects on Molecular Properties 4104 8. Conclusions 4105 9. References 4105 Ola Engkvist finished his Ph.D. degree in 1997 at the

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