2,945 research outputs found
Spectroscopic accuracy directly from quantum chemistry: application to ground and excited states of beryllium dimer
We combine explicit correlation via the canonical transcorrelation approach
with the density matrix renormalization group and initiator full configuration
interaction quantum Monte Carlo methods to compute a near-exact beryllium dimer
curve, {\it without} the use of composite methods. In particular, our direct
density matrix renormalization group calculations produce a well-depth of
=931.2 cm which agrees very well with recent experimentally derived
estimates =929.7~cm [Science, 324, 1548 (2009)] and
=934.6~cm [Science, 326, 1382 (2009)]], as well the best composite
theoretical estimates, =938~cm [J. Phys. Chem. A, 111,
12822 (2007)] and =935.1~cm [Phys. Chem. Chem. Phys., 13,
20311 (2011)]. Our results suggest possible inaccuracies in the functional form
of the potential used at shorter bond lengths to fit the experimental data
[Science, 324, 1548 (2009)]. With the density matrix renormalization group we
also compute near-exact vertical excitation energies at the equilibrium
geometry. These provide non-trivial benchmarks for quantum chemical methods for
excited states, and illustrate the surprisingly large error that remains for
1 state with approximate multi-reference configuration
interaction and equation-of-motion coupled cluster methods. Overall, we
demonstrate that explicitly correlated density matrix renormalization group and
initiator full configuration interaction quantum Monte Carlo methods allow us
to fully converge to the basis set and correlation limit of the
non-relativistic Schr\"odinger equation in small molecules
H2O contents and hydrogen isotopic composition of apatite crystals from L, LL5-6 ordinary chondrites.
第3回極域科学シンポジウム/第35回南極隕石シンポジウム 11月30日(金) 国立国語研究所 2階講
The manifest association structure of the single-factor model: insights from partial correlations
The association structure between manifest variables arising from the single-factor model is investigated using partial correlations. The additional insights to the practitioner provided by partial correlations for detecting a single-factor model are discussed. The parameter space for the partial correlations is presented, as are the patterns of signs in a matrix containing the partial correlations that are not compatible with a single-factor model
Analysis of Bidirectional Associative Memory using SCSNA and Statistical Neurodynamics
Bidirectional associative memory (BAM) is a kind of an artificial neural
network used to memorize and retrieve heterogeneous pattern pairs. Many efforts
have been made to improve BAM from the the viewpoint of computer application,
and few theoretical studies have been done. We investigated the theoretical
characteristics of BAM using a framework of statistical-mechanical analysis. To
investigate the equilibrium state of BAM, we applied self-consistent signal to
noise analysis (SCSNA) and obtained a macroscopic parameter equations and
relative capacity. Moreover, to investigate not only the equilibrium state but
also the retrieval process of reaching the equilibrium state, we applied
statistical neurodynamics to the update rule of BAM and obtained evolution
equations for the macroscopic parameters. These evolution equations are
consistent with the results of SCSNA in the equilibrium state.Comment: 13 pages, 4 figure
Absolute value measurement of ion-scale turbulence by two-dimensional phase contrast imaging in Large Helical Device
Absolute value measurements of turbulence amplitude in magnetically confined
high-temperature plasmas can effectively explain turbulence-driven transport
characteristics and their role in plasma confinements. Two-dimensional phase
contrast imaging (2D-PCI) is a technique to evaluate the space-time spectrum of
ion-scale electron density fluctuation. However, absolute value measurement of
turbulence amplitude has not been conducted owing to the nonlinearity of the
detector. In this study, the absolute measurement method proposed in the
previous study is applied to turbulence measurement results in the large
helical device. As a result, the localized turbulence amplitude at
m is approximately m,
which is 0.02\% of the electron density. In addition, the evaluated poloidal
wavenumber spectrum is almost consistent, within a certain error range, the
spectrum being calculated using a nonlinear gyrokinetic simulation. This result
is the first to the best of our knowledge to quantitatively evaluate turbulence
amplitudes measured by 2D-PCI and compare with simulations
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