9,418 research outputs found
Lie algebra and invariant tensor technology for g2
Proceeding in analogy with su(n) work on lambda matrices and f- and
d-tensors, this paper develops the technology of the Lie algebra g2, its seven
dimensional defining representation gamma and the full set of invariant tensors
that arise in relation thereto. A comprehensive listing of identities involving
these tensors is given. This includes identities that depend on use of
characteristic equations, especially for gamma, and a good body of results
involving the quadratic, sextic and (the non-primitivity of) other Casimir
operators of g2.Comment: 29 pages, LaTe
AN EXPERIMENTAL INVESTIGATION IN AN ATMOSPHERE ENTRY SIMULATOR OF NYLON AS AN ABLATIVE MATERIAL FOR BALLISTIC MISSILES
Investigation in atmosphere entry simulator of nylon as ablative material for ballistic missile
Van der Waals forces in density functional theory: perturbational long-range electron interaction corrections
Long-range exchange and correlation effects, responsible for the failure of
currently used approximate density functionals in describing van der Waals
forces, are taken into account explicitly after a separation of the
electron-electron interaction in the Hamiltonian into short- and long-range
components. We propose a "range-separated hybrid" functional based on a local
density approximation for the short-range exchange-correlation energy, combined
with a long-range exact exchange energy. Long-range correlation effects are
added by a second-order perturbational treatment. The resulting scheme is
general and is particularly well-adapted to describe van der Waals complexes,
like rare gas dimers.Comment: 8 pages, 1 figure, submitted to Phys. Rev.
On the Energetics of the HCO + C CH + CO Reaction and Some Astrochemical Implications
We explore the energetics of the titular reaction, which current
astrochemical databases consider open at typical dense molecular (i.e., dark)
cloud conditions. As is common for reactions involving the transfer of light
particles, we assume that there are no intersystem crossings of the potential
energy surfaces involved. In the absence of any such crossings, we find that
this reaction is endoergic and will be suppressed at dark cloud temperatures.
Updating accordingly a generic astrochemical model for dark clouds changes the
predicted gas-phase abundances of 224 species by greater than a factor of 2. Of
these species, 43 have been observed in the interstellar medium. Our findings
demonstrate the astrochemical importance of determining the role of intersystem
crossings, if any, in the titular reaction.Comment: Accepted for publication in ApJ; 14 pages, 2 figures, and 1 tabl
Learning and Communication in Sender-Reciever Games: An Economic Investigation
This paper compares the performance of stimulus response (SR) and belief-based learning (BBL) using data from game theory experiments. The environment, extensive form games played in a population setting, is novel in the empirical literature on learning in games. Both the SR and BBL models fit the data reasonably well in common interest games with history while the test results accept SR and reject BBL in games with no history and in all but one of the divergent interest games. Estimation is challenging since the likelihood function is not globally concave and the results may be subject to convergence bias.econometrics;game theory and experiments
Discrete breathers in polyethylene chain
The existence of discrete breathers (DBs), or intrinsic localized modes
(localized periodic oscillations of transzigzag) is shown. In the localization
region periodic contraction-extension of valence C-C bonds occurs which is
accompanied by decrease-increase of valence angles. It is shown that the
breathers present in thermalized chain and their contribution dependent on
temperature has been revealed.Comment: 5 pages, 6 figure
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