Jens Oddershede

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Various methods for the inclusion of relativistic effects in the calculation of NMR parameters are discussed. Benchmark values for the NMR shieldings and indirect nuclear spin]spin coupling tensors for the hydrogen halides are calculated using the four-component relativistic random phase approximation method. Apart from recovering the well-known trend of(More)
Based on the Ehrenfest theorem, an equation of motion that takes relaxation into account has been presented in wave-function theory, and the resulting response functions are nondivergent in the off-resonant as well as the resonant regions of optical frequencies. The derivation includes single- and multideterminant reference states. When applied to electric(More)
Relativistic four-component random phase approximation ~RPA! calculations of indirect nuclear spin–spin coupling constants in MH4 (M5C, Si, Ge, Sn, Pb) and Pb~CH3!3H are presented. The need for tight s-functions also in relativistic four-component calculations is verified and explained, and the effect of omission of ~SS–LL! and ~SS–SS! two-electron(More)
We present the first results from quantum-chemical calculation of a vibrational g-factor; the calculations were performed at the level of full configuration interaction using a basis set of aug-cc-pVQZ quality. The theoretical results are consistent with experimental results from analysis of pure rotational and vibration-rotational spectra of dihydrogen in(More)
In this contribution, we consider the interaction of glycine, a small, model biomolecule, and its zwitterion with fast ion radiation. The object of the study is to determine the differences in properties among various conformers and orientations of the neutral molecule and the zwitterion and to determine if these differences will have implications in terms(More)
We suggest a method for determination of the mean excitation energies of several biomolecules, such as amino acids, using a Bragg-like sum rule developed for molecular fragments or functional groups. Because the fragment composition of many bio-organic molecules is very similar, we find that many of them, including the amino acids, have similar mean(More)
The lowest electronic transitions in H2, CH’ and Be have been analysed in terms of the individual contributions to excitation energies and transition moments in a second-order polarisation propagator calculation and in a second-order diagrammatic calculation based on both the full particle-hole propagator matrix and on the single-transition approximation.(More)
The linear and quadratic response functions have been derived for an exact state, based on an exponential parametrization of the time evolution consisting of products of exponentials for orbital rotations and for higher-order excitations. Truncating the linear response function such that the response function itself and its pole structure is correct to(More)
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