Mark R. Pederson

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We report first-principles all-electron density-functional-based studies of the electronic structure, magnetic ordering, and anisotropy for the V15 molecular magnet. From these calculations, we determine a Heisenberg Hamiltonian with five antiferromagnetic and one ferromagnetic exchange couplings. We perform direct diagonalization to determine the(More)
We report first-principles density-functional calculations for hydroquinone (HQ), indolequinone (IQ), and semiquinone (SQ). These molecules are believed to be the basic building blocks of the eumelanins, a class of biomacromolecules with important biological functions (including photoprotection) and with the potential for certain bioengineering(More)
*Soft Condensed Matter Physics Group, University of Queensland Department of Physics, St. Lucia Campus, Brisbane, QLD 4072, Australia Theory of Condensed Matter Physics Group, University of Queensland Department of Physics St. Lucia Campus, Brisbane, QLD 4072, Australia Center for Computational Materials Science, Naval Research Laboratory, Washington, D.C.(More)
We report Kondo resonances in the conduction of single-molecule transistors based on transition metal coordination complexes. We find Kondo temperatures in excess of 50 K, comparable to those in purely metallic systems. The observed gate dependence of the Kondo temperature is inconsistent with observations in semiconductor quantum dots and a simple(More)
We present a study on the electronic structure of a biology-inspired molecular triad which shows promises in replicating photosynthesis process in the laboratory. The triad contains three different units--C60, porphyrin, and beta-carotenoid. We present its geometrical and electronic structure, dipole moments, optical absorption spectrum, and polarizability(More)
The quantum states in metal clusters are grouped into bunches of close-lying eigenvalues, termed electronic shells, similar to those of atoms. Filling of the electronic shells with paired electrons results in local minima in energy to give stable species called magic clusters. This led to the realization that selected clusters mimic chemical properties of(More)
Cluster ions, CaN and Ca 2þ N , containing up to N = 8 atoms are studied within density functional theory. Ground and first excited states, and ionization energies are reported for all sizes. At zero temperature Ca2þ 3 and Ca 2þ 4 are linear, whereas Ca 2þ 5 through Ca 2þ 7 undergo structural transitions from 3D-configurations into linear ions below 600 K.(More)
Standard spin-density functionals for the exchange-correlation energy of a many-electron ground state make serious self-interaction errors which can be corrected by the Perdew-Zunger self-interaction correction (SIC). We propose a size-extensive construction of SIC orbitals which, unlike earlier constructions, makes SIC computationally efficient, and a true(More)
We present a nonperturbative derivation for the primary contribution to the vibrational polarizability for molecules, clusters, and other finite systems. Using a double-harmonic approximation and a finite-field approach the vibrational polarizability is calculated within the generalized gradient approximation to the density functional theory for a variety(More)