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No abstract available

[en] Results of density-functional calculations on Pd_nH_m, n, m ≤ 2, clusters are reported. Special emphasis is put on the changes in H-H interactions due to the presence of palladium. It is verified that the calculations can reproduce general trends (with some limitations) in Pd-Pd, H-H and Pd-H interactions. An increase in H-H repulsion when a H₂ molecule is brought close to Pd surroundings indicates that cold D + D fusion in Pd is unlikely

[en] It is shown that the reaction field induced in an atom by a strong magnetic field is of order Bα in atomic units (for magnetic field strength B and fine structure constant α). The reaction field causes a dipole-dipole interatomic potential energy to exist between a pair of atoms of order B^3/2α^7/2, such that B must be of order α^-7/3 for the interatomic energy to be of order one atomic unit. B of this order corresponds to a field strength of 1.66 x 10¹² G, which is within the regime of field strengths considered in recent studies of atoms and molecules in the presence of a strong magnetic field

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[en] The problem of long-range configuration interaction between ionic and covalent states is considered. The existing methods for calculation of this interaction are discussed. An asymptotically exact expression for the long-range configuration interaction at the crossing point of diabatic ionic and covalent potentials is derived. Using this expression the adiabatic energy splitting at the crossing point for H*+H, M+H, and M+O systems (M = alkali atom) is calculated. The results are compared with those obtained by LCAO and variational calculations

[en] Utilizing the icosahedral symmetry of the C₆₀ molecule by amalgamating two methods, we solve the vibrational eigenfrequency problem for carbon-60 to obtain exact algebraic expressions for the characteristic polynomials of the vibration. The inter-atomic interaction consists of four force constants, two for bond-stretching and two for angle-oscillation. (orig.)

[en] The report presents an Fe-Cr interatomic potential to model high-Cr ferritic alloys. The potential is fitted to thermodynamic and point-defect properties obtained from density functional theory (DFT) calculations and experiments. The developed potential is also benchmarked against other potentials available in literature. It shows particularly good agreement with the DFT obtained mixing enthalpy of the random alloy, the formation energy of intermetallics and experimental excess vibrational entropy and phase diagram. In addition, DFT calculated point-defect properties, both interstitial and substitutional, are well reproduced, as is the screw dislocation core structure. As a first validation of the potential, we study the precipitation hardening of Fe-Cr alloys via static simulations of the interaction between Cr precipitates and screw dislocations. It is concluded that the description of the dislocation core modification near a precipitate might have a significant influence on the interaction mechanisms observed in dynamic simulations.

[en] The interatomic relaxation (IR) effects of two-site double core hole (tsDCH) states in selected molecules with a polarizable unit have been systematically investigated using ab initio calculations. The IR effects are analysed by varying the size of this polarizable unit and its position relative to the DCHs. The systems with the DCHs located on the opposite sides of the polarizable unit show large negative IR energies, while those on the same side of the polarizable unit have smaller negative IR effects. Here, the IR energies can even be positive if the polarizable unit is large enough. The generalized Wagner plots of tsDCH states are used to visualize the trend of the IR effects in the molecules studied. (paper)

No abstract available