55 research outputs found
Comparative studies of the magnetic dipole and electric quadrupole hyperfine constants for the ground and low lying excited states of ^{25}Mg^{+}
We have employed the relativistic coupled cluster theory to calculate the
magnetic dipole and electric quadrupole hyperfine constants for the ground and
low lying excited states of singly ionized magnesium. Comparison with
experimental and the other theoretical results are done and predictions are
also made for a few low lying excited states which could be of interest. We
have made comparative studies of the important many body effects contributing
to the hyperfine constants for the different states of the ion.Comment: 3 figures, Late
Relativistic and correlation effects in atoms
This review article deals with some case studies of relativistic and
correlation effects in atomic systems. After a brief introduction to
relativistic many-electron theory, a number of applications ranging from
correlation energy to parity non-conservation in atoms are considered. There is
a special emphasis on relativistic coupled-cluster theory as most of the
results presented here are based on it.Comment: Review article, 4 eps figures, latex 2
Relativistic Coupled-Cluster Theory of Atomic Parity Nonconservation: Application to Ba
We report the result of our {\it ab initio} calculation of the parity nonconserving electric dipole transition amplitude in
based on relativistic coupled-cluster theory. Considering
single, double and partial triple excitations, we have achieved an accuracy of
less than one percent. If the accuracy of our calculation can be matched by the
proposed parity nonconservation experiment in Ba for the above
transition,then the combination of the two results would provide an independent
non accelerator test of the Standard Model of particle physics.Comment: 4 pages, 1 figure, Submitted to PR
Carbon-bearing silicate melt at deep mantle conditions
Knowledge about the incorporation and role of carbon in silicate magmas is crucial for our understanding of the deep mantle processes. CO bearing silicate melting and its relevance in the upper mantle regime have been extensively explored. Here we report first-principles molecular dynamics simulations of MgSiO melt containing carbon in three distinct oxidation states - CO , CO, and C at conditions relevant for the whole mantle. Our results show that at low pressures up to 15 GPa, the carbon dioxide speciation is dominated by molecular form and carbonate ions. At higher pressures, the dominant species are silicon-polyhedral bound carbonates, tetrahedral coordination, and polymerized di-carbonates. Our results also indicate that CO component remains soluble in the melt at high pressures and the solution is nearly ideal. However, the elemental carbon and CO components show clustering of carbon atoms in the melt at high pressures, hinting towards possible exsolution of carbon from silicate melt at reduced oxygen contents. Although carbon lowers the melt density, the effect is modest at high pressures. Hence, it is likely that silicate melt above and below the mantle transition zone, and atop the core-mantle boundary could efficiently sequester significant amounts of carbon without being gravitationally unstable. 2 3 2
Ab initio determination of the lifetime of the state f or by relativistic many-body theory
Relativistic coupled-cluster(RCC) theory has been employed to calculate the
life time of the state of single ionized lead() to an
accurac y of 3% and compared with the corresponding value obtained using second
order r elativistic many-body perturbation theory(RMBPT). This is one of the
very few ap plications of this theory to excited state properties of heavy
atomic systems. C ontributions from the different electron correlation effects
are given explicitl y
C-H bond functionalization under electrochemical flow conditions
Electrochemical CâH functionalization is a rapidly growing area of interest in organic synthesis. To achieve maximum atom economy, the flow electrolysis process is more sustainable. This allows shorter reaction times, safer working environments, and better selectivities. Using this technology, the problem of overoxidation can be reduced and less emergence of side products or no side products are possible. Flow electro-reactors provide high surface-to-volume ratios and contain electrodes that are closely spaced where the diffusion layers overlap to give the desired product, electrochemical processes can now be managed without the need for a deliberately added supporting electrolyte. Considering the importance of flow electrochemical CâH functionalization, a comprehensive review is presented. Herein, we summarize flow electrolysis for the construction of CâC and CâX (X=O, N, S, and I) bonds formation. Also, benzylic oxidation and access to biologically active molecules are discussed
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