Lithium Atom (lithium + atom)

Distribution by Scientific Domains


Selected Abstracts


Interaction of Triatomic Germanium with Lithium Atoms: Electronic Structure and Stability of Ge3Lin Clusters

CHEMINFORM, Issue 32 2007
G. Gopakumar
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]


An accurate few-parameter ground state wave function for the lithium atom

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 13 2009
Nicolais L. Guevara
Abstract A simple, seven-parameter trial function is proposed for a description of the ground state of the Lithium atom. It includes both spin functions. Inter-electronic distances appear in exponential form as well as in a pre-exponential factor, and the necessary energy matrix elements are evaluated by numerical integration in the space of the relative coordinates. Encouragingly accurate values of the energy and the cusp parameters as well as for some expectation values are obtained. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source]


Structural Studies of Lithium Telluro- and Seleno-Phosphorus Compounds

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2003
Robert P. Davies
Abstract Lithium tellurophosphinite [Ph2PTe][Li(TMEDA)1.33(THF)1.33] (4), ditellurophosphinate, [Ph2PTe2][Li(THF)3.5(TMEDA)0.25] (5), and selenotellurophosphinate [Ph2P(Se)Te][Li(THF)2(TMEDA)] (6) complexes have been prepared from the insertion/oxidation reactions of lithiated secondary phosphanes with elemental chalcogens and characterised by X-ray crystallography. Compounds 4,6 contain no tellurium,lithium bonding interactions in the solid state, instead existing as ion-separated species with THF/TMEDA-solvated lithium cations. Reaction of dilithiated primary phosphanes with more than three equivalents of elemental selenium gives [{(c -C6H11)P(Se)(SeLi)}2·2TMEDA] (7) via a phosphorus-phosphorus coupling reaction. Solid state characterisation of 7 reveals the organo groups in the tetradentate tetraselenohypodisphosphinate ligand to be in an anti conformation to one another and each lithium atom to be coordinated by two selenium atoms, one from each of the diselenophosphinate groups. Multinuclear NMR spectroscopic data are consistent with retention of the solid-state structures of 4,7 in solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]


Geometrical properties of nodal surfaces of many-electron wave functions

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2010
Nikolai D. Chuvylkin
Abstract Hypothesis of the exclusion of equipotential surfaces for many-electron wave functions (MWF) has been enunciated. This hypothesis clarifies the physical meaning of the Pauli exclusion principle and opens the way for future progress of new quantum-chemical methods for the construction of approximate MWFs differing from the traditional Hartree,Fock approximation. The equipotential surface exclusion principle has been tested on traditional representative "test systems" of quantum mechanics: the helium atom, the lithium atom, and the hydrogen molecule. Judging by the results of these tests, the use of the suggested approach can lead to a considerable increase in the efficiency of high-accuracy quantum-chemical calculations. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source]


An accurate few-parameter ground state wave function for the lithium atom

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 13 2009
Nicolais L. Guevara
Abstract A simple, seven-parameter trial function is proposed for a description of the ground state of the Lithium atom. It includes both spin functions. Inter-electronic distances appear in exponential form as well as in a pre-exponential factor, and the necessary energy matrix elements are evaluated by numerical integration in the space of the relative coordinates. Encouragingly accurate values of the energy and the cusp parameters as well as for some expectation values are obtained. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source]


Test and modification of the van der Waals' radii employed in the default PCM model

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2008
Wei-Hua Mu
Abstract High level ab initio calculations at the B3LYP/6-311++G(d,p) and MP2(full)/6-311++G(d,p) levels employing PCM/UA0 model with different van der Waals' radii for the systems that contain lithium atoms have been carried out, in order to see if the van der Waal's radius for lithium atom employed in the default PCM/UA0 model is proper or not. Comparative analysis indicated that the van der Waals' radius for alkali metals, especially for lithium atom in the default PCM/UA0 model within the Gaussian 03 package, is too small, which causes erroneous redundant imaginary frequencies (RIFs) in the characterization of Li-containing compounds from moderate to big size. A new set of van der Waals' atomic radii based on QTAIM, proposed by Bader, was suggested for a better choice in the characterization of compounds containing alkali metals, for which it can effectively avoid the erroneous RIFs for corresponding geometries of these Li-containing systems. © 2008 Wiley Periodicals, Inc. Int. J. Quantum Chem, 2008 [source]


On the Dichotomic Reactivity of Lithiated Styrene Oxide: A Computational and Multinuclear Magnetic Resonance Investigation

CHEMISTRY - A EUROPEAN JOURNAL, Issue 32 2009
Vito Capriati Prof.
Abstract A multinuclear magnetic resonance investigation, supported by density functional theory calculations, has been synergically used to investigate the configurational stability, reactivity and aggregation states of ,-lithiated styrene oxide in THF at 173,K. NMR studies on ,-lithiated [,,,- 13C2]styrene oxide (also in an enantiomerically enriched form) proved that in THF this oxiranyllithium is mainly present as a solvated monomeric species in equilibrium with a complex mixture of stereoisomeric dimeric aggregates, as well as with bridged and tetrameric aggregates. The fact that some C,Li bonds are partially broken in some stereoisomers reduces their symmetry and complicates the NMR spectra: two diastereoisomers each having a pair of diastereotopic carbon atoms slowly inverting at the lithium atom in absence of tetramethylethylenediamine (TMEDA) have been detected. A (13C,7Li)-HMQC experiment to correlate 7Li and 13C resonances of the various aggregates has been performed for the first time. From natural bond analysis, the monomeric aggregate was proven to have a lower carbenoid character with respect to bridged O-coordinated dimeric aggregates. The employment of suitable experimental conditions in terms of concentration, temperature and the presence or not of TMEDA are crucial to mitigate at the best the "carbene-like" reactivity of lithiated styrene oxide toward intermolecular CLi insertions, eliminative dimerisation reactions and ring-opening reactions. A two-step mechanism for the deprotonation of styrene oxide by sBuLi in THF has been proposed and discussed as well as competitive side reactions. [source]


Test and modification of the van der Waals' radii employed in the default PCM model

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2008
Wei-Hua Mu
Abstract High level ab initio calculations at the B3LYP/6-311++G(d,p) and MP2(full)/6-311++G(d,p) levels employing PCM/UA0 model with different van der Waals' radii for the systems that contain lithium atoms have been carried out, in order to see if the van der Waal's radius for lithium atom employed in the default PCM/UA0 model is proper or not. Comparative analysis indicated that the van der Waals' radius for alkali metals, especially for lithium atom in the default PCM/UA0 model within the Gaussian 03 package, is too small, which causes erroneous redundant imaginary frequencies (RIFs) in the characterization of Li-containing compounds from moderate to big size. A new set of van der Waals' atomic radii based on QTAIM, proposed by Bader, was suggested for a better choice in the characterization of compounds containing alkali metals, for which it can effectively avoid the erroneous RIFs for corresponding geometries of these Li-containing systems. © 2008 Wiley Periodicals, Inc. Int. J. Quantum Chem, 2008 [source]