5,127 research outputs found
Generalized Hamilton-Jacobi equations for nonholonomic dynamics
Employing a suitable nonlinear Lagrange functional, we derive generalized
Hamilton-Jacobi equations for dynamical systems subject to linear velocity
constraints. As long as a solution of the generalized Hamilton-Jacobi equation
exists, the action is actually minimized (not just extremized)
On the Dipole Swing and the Search for Frame Independence in the Dipole Model
Small-x evolution in QCD is conveniently described by Mueller's dipole model
which, however, does not include saturation effects in a way consistent with
boost invariance. In this paper we first show that the recently studied zero
and one dimensional toy models exhibiting saturation and explicit boost
invariance can be interpreted in terms positive definite k-> k+1 dipole
vertices. Such k-> k+1 vertices can in the full model be generated by combining
the usual dipole splitting with k-1 simultaneous dipole swings. We show that,
for a system consisting of N dipoles, one needs to combine the dipole splitting
with at most N-1 simultaneous swings in order to generate all colour
correlations induced by the multiple dipole interactions
Precision calculation of energy levels for four-valent Si I
We report results of the calculation of the low-lying levels of neutral Si
using a combination of the configuration interaction and many-body perturbation
theory (CI+MBPT method). We treat Si I as an atom with four valence electrons
and use two different starting approximations, namely and .
We conclude that both approximations provide comparable accuracy, on the level
of 1%
Electric dipole moment of the electron in YbF molecule
Ab initio calculation of the hyperfine, P-odd, and P,T-odd constants for the
YbF molecule was performed with the help of the recently developed technique,
which allows to take into account correlations and polarization in the
outercore region. The ground state electronic wave function of the YbF molecule
is found with the help of the Relativistic Effective Core Potential method
followed by the restoration of molecular four-component spinors in the core
region of ytterbium in the framework of a non-variational procedure. Core
polarization effects are included with the help of the atomic Many Body
Perturbation Theory for Yb atom. For the isotropic hyperfine constant A,
accuracy of our calculation is about 3% as compared to the experimental datum.
The dipole constant Ad (which is much smaller in magnitude), though better than
in all previous calculations, is still underestimated by almost 23%. Being
corrected within a semiempirical approach for a perturbation of 4f-shell in the
core of Yb due to the bond making, this error is reduced to 8%. Our value for
the effective electric field on the unpaired electron is 4.9 a.u.=2.5E+10 V/cm.Comment: 7 pages, REVTE
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