334 research outputs found
ABINITIO CALCULATIONS OF SINGLY EXCITED-STATES OF ATOMS WITH AUGMENTED FUESS-TYPE BASIS FUNCTIONS
No full textYURTSEVER E, Faisal F. ABINITIO CALCULATIONS OF SINGLY EXCITED-STATES OF ATOMS WITH AUGMENTED FUESS-TYPE BASIS FUNCTIONS. CHEMICAL PHYSICS LETTERS. 1979;66(1):104-107
Neutral and ionic dopants in helium clusters: interaction forces for the Li-2(a(3)Sigma(+)(u))-He and Li-2(+)(X-2 Sigma(+)(g))-He complexes
No full textThe potential energy surface (PES) describing the interactions between Li-2((1)Sigma(u)(+)) and He-4 and an extensive study of the energies and str uctures of a set of small clusters, Li-2(He)(n), were reported in a previous series of publications. In the present work, the same analysis is extended to the case of the excited Li-2(a(3)Sigma(u)(+)) and of the ionized Li-2(+) (X(2)Sigma(g)(+)) moiety. Calculated interaction potentials for the two title syst ems and the corresponding fitting of the computed points are shown. For both surfaces the MP4 method with cc-pV5Z basis sets has been used to generate an e xtensive range of radial/angular coordinates of the two-dimensional PESs which describe rigid rotor molecular dopants interacting with one He partner
SYNCHRONOUS 1,4-ADDITION OF METHYLENE TO CIS-BUTADIENE
No full textSchoeller W, YURTSEVER E. SYNCHRONOUS 1,4-ADDITION OF METHYLENE TO CIS-BUTADIENE. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. 1978;100(24):7548-7550
Ionic dimers in He droplets: Interaction potentials for Li-2(+)-He,Na-2(+)-He, and K-2(+)-He and stability of the smaller clusters
No full textWe present post Hartree-Fock calculations of the potential energy surfaces (PESs) for the ground electronic states of the three alkali dimer ions Li-2(+), Na-2(+), and K-2(+) interacting with neutral helium. The calculations were carried out for the frozen molecular equilibrium geometries and for an extensive range of the remaining two Jacobi coordinates, R and theta, for which a total of about 1000 points is generated for each surface. The corresponding raw data were then fitted numerically to produce analytic expressions for the three PESs, which were in turn employed to evaluate the bound states of the three trimers for their J=0 configurations: The final spatial features of such bound states are also discussed in detail. The possible behavior of additional systems with more helium atoms surrounding the ionic dopants is gleaned from further calculations on the structural stability of aggregates with up to six He atoms. The validity of a sum-of-potential approximation to yield realistic total energies of the smaller cluster is briefly discussed vis-a-vis the results from many-body calculations. (c) 2006 American Institute of Physics
PLANAR SINGLET TRIMETHYLENEMETHANE .1. AZA-SUBSTITUTION
No full textSchoeller W, YURTSEVER E, SHILLADY DD. PLANAR SINGLET TRIMETHYLENEMETHANE .1. AZA-SUBSTITUTION. NOUVEAU JOURNAL DE CHIMIE-NEW JOURNAL OF CHEMISTRY. 1979;3(10):603-606
Quantum structuring of4He atoms around ionic dopants: Energetics of Li+, Na+ and K+ from stochastic calculations
No full textBosonic helium droplets with cationic impurities: Onset of electrostriction and snowball effects from quantum calculations
No full textVariational Monte Carlo and diffusion Monte Carlo calculations have been carried out for cations such as Li+, Na+, and K+ as dopants of small helium clusters over a range of cluster sizes up to about 12 solvent atoms. The interaction has been modeled through a sum-of-potential picture that disregards higher order effects beyond atom-atom and atom-ion contributions. The latter were obtained from highly correlated ab initio calculations over a broad range of interatomic distances. This study focuses on two of the most striking features of the microsolvation in a quantum solvent of a cationic dopant: electrostriction and snowball effects. They are discussed here in detail and in relation with the nanoscopic properties of the interaction forces at play within a fully quantum picture of the cluster features
Bosonic helium droplets with cationic impurities: Onset of electrostriction and snowball effects from quantum calculations
No full textVariational Monte Carlo and diffusion Monte Carlo calculations have been carried out for cations such as Li+, Na+, and K+ as dopants of small helium clusters over a range of cluster sizes up to about 12 solvent atoms. The interaction has been modeled through a sum-of-potential picture that disregards higher order effects beyond atom-atom and atom-ion contributions. The latter were obtained from highly correlated ab initio calculations over a broad range of interatomic distances. This study focuses on two of the most striking features of the microsolvation in a quantum solvent of a cationic dopant: electrostriction and snowball effects. They are discussed here in detail and in relation with the nanoscopic properties of the interaction forces at play within a fully quantum picture of the cluster features
Solvation of K+ in helium droplets
No full textSolvation of K+ in helium droplets is studied by classical simulation methods. We have previously shown that additive potentials can be used to describe structures of helium droplets when an ionic species is present. Here, we present an accurate ab-initio potential for the K+ - He interaction. Global minima of KHen+ for up to n=70 are searched for employing Basin Hopping Monte Carlo simulations with a random growth scheme. The extent of the solvation is analyzed. A clear formation of two shells with 15 and 23 atoms is detected
Vibrational quenching at ultralow energies: Calculations of the Li-2((1)Sigma(+)(g);nu >> 0)+He superelastic scattering cross sections
No full textAccurate quantum calculations have been carried out at ultralow energies (from 10(-2) to 10(-6) cm(-1)) for the vibrational deexcitation of Li-2((1)Sigma(+)(g)) by collisions with He, starting from a broad range of initial highly excited vibrational levels. The results indicate the clear dominance of a few transitions with the smallest Delta nu changes and show the overall deexcitation cross sections to markedly depend on the initial vibrational state of the molecule, in line with earlier results on H-2+He [Balakrishan Phys. Rev. Lett. 80, 3224 (1998)] vibrational quenching. A connection is made with very recent measurements on the vibrational quenching of ultracold Cs-2 molecules in optical traps that were instead found to behave in a very different manner. Numerical experiments on the present system as well as on the H-3 reaction strongly suggest a possible explanation for such differences
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