Search results for "Diagonal"

The barrier height of the F+H2 reaction revisited: coupled-cluster and multireference configuration-interaction benchmark calculations.

2008

Large scale coupled-cluster benchmark calculations have been carried out to determine the barrier height of the F+H2 reaction as accurately as possible. The best estimates for the barrier height of the linear and bent transition states amount to 2.16 and 1.63 kcal/mol, respectively. These values include corrections for core correlation, scalar-relativistic effects, spin-orbit effects, as well as the diagonal Born-Oppenheimer correction. The CCSD(T) basis-set limits are estimated using extrapolation techniques with augmented quintuple and sextuple-zeta basis sets, and remaining N-electron errors are determined using coupled-cluster singles, doubles, triples, quadruples calculations with up t…

The tensor of interaction of a two-level system with an arbitrary strain field

2007

The interaction between two-level systems (TLS) and strain fields in a solid is contained in the diagonal matrix element of the interaction hamiltonian, $\delta$, which, in general, has the expression $\delta=2[\gamma]:[S]$, with the tensor $[\gamma]$ describing the TLS ``deformability'' and $[S]$ being the symmetric strain tensor. We construct $[\gamma]$ on very general grounds, by associating to the TLS two objects: a direction, $\hat\bt$, and a forth rank tensor of coupling constants, $[[R]]$. Based on the method of construction and on the invariance of the expression of $\delta$ with respect to the symmetry transformation of the solid, we conclude that $[[R]]$ has the same structure as …

Quantum chemical calculations of formyl radicals

1975

The ground state (2 A′) of the fluoroformyl radical, FCO, has been investigated by the unrestricted Hartree-Fock method. Pulay's force method for open-shell systems has been applied to calculate the complete quadratic force field and the diagonal cubic force constants. The force relaxation method has been used to determine the equilibrium geometry of FCO: . Adjusting the diagonal force constants to the observed vibrational frequencies of 19F12C16O and taking the values for the off-diagonal force constants from the UHF calculations, the force field of FCO is found to be: . This force field is compared with experiment and with the force fields of HCO, H2CO, and F2CO. The ground state of the F…

Benchmark Thermochemistry of the Hydroperoxyl Radical

2004

A theoretical estimation of the enthalpy of formation for the hydroperoxyl radical is presented. These results are based on CCSD(T)/aug-cc-pCV5Z calculations extrapolated to the basis-set limit with additional corrections. Anharmonic vibrational zero-point energies, scalar relativistic, spin -orbit coupling, and diagonal BornOppenheimer corrections are further used to correct the extrapolated term energies, as well as various empirical corrections that account for correlation effects not treated at the CCSD(T) level. We estimate that ¢fH° ) 3.66 ( 0.10 kcal mol -1 (¢fH° ) 2.96 ( 0.10 kcal mol -1 ) using several reaction schemes. Significantly, it appears to be necessary to include effects o…

A note on rank 2 diagonals

2020

<p>We solve two questions regarding spaces with a (G<sub>δ</sub>)-diagonal of rank 2. One is a question of Basile, Bella and Ridderbos about weakly Lindelöf spaces with a G<sub>δ</sub>-diagonal of rank 2 and the other is a question of Arhangel’skii and Bella asking whether every space with a diagonal of rank 2 and cellularity continuum has cardinality at most continuum.</p>

Quadrupole deformation of Xe-130 measured in a Coulomb-excitation experiment

2020

Physical review / C 102(5), 054304 (2020). doi:10.1103/PhysRevC.102.054304

Focal plane array infrared camera transfer function calculation and image restoration

2004

Infrared images often present distortions induced by the measurement system. Image processing is thus an essential part of infrared measurements. A distortion model based on a convolution product is presented. The analytical form of the convolution kernel has been obtained from an image formation theory, along with an analysis of the sampling of the focal plane array camera detector's matrix. Image restoration is an ill-posed problem, and its solution can be obtained using regularization methods. In this work, image restoration is performed using a variation of Tikhonov regularization that makes use of the particular form of the convolution kernel matrix, which is built as a block-circulant…

Dipolar NLO-phores with large off-diagonal components of the second-order polarizability tensor

1997

Toward computability of trace distance discord

2014

It is known that a reliable geometric quantifier of discord-like correlations can be built by employing the so-called trace distance. This is used to measure how far the state under investigation is from the closest "classical-quantum" one. To date, the explicit calculation of this indicator for two qubits was accomplished only for states such that the reduced density matrix of the measured party is maximally mixed, a class that includes Bell-diagonal states. Here, we first reduce the required optimization for a general two-qubit state to the minimization of an explicit two-variable function. Using this framework, we show next that the minimum can be analytically worked out in a number of r…

AbsolutelyLexpq - Summing Norms of Diagonal Operators inlr and Limit Orders ofLexp - Summing Operators

2001

We compute the absolutely L – summing norms of the diagonal operators acting on lr (1 ≤ q, r < ∞) and determine the limit orders of the absolutely Lexp – summing operators.