نتایج جستجو برای: electron density

تعداد نتایج: 685167  

Journal: :Biochimica et Biophysica Acta (BBA) - Bioenergetics 2002

Journal: :The Journal of chemical physics 2005
P M W Gill A T B Gilbert S W Taylor G Friesecke M Head-Gordon

Many quantum chemical methods, both wave function and density based, rely on an expansion of elements of the electron density in an auxiliary basis. However, little is known about the analytical behavior of the expansion coefficients and, in particular, about their rate of decay with distance. We discuss an exactly solvable model system and characterize the expansion coefficients for various fi...

2017
A. M. Persoon D. A. Gurnett W. S. Kurth G. B. Hospodarsky J. B. Groene P. Canu M. K. Dougherty

2002
Thomas C. Terwilliger

Statistical density modification is a technique for phase improvement through a calculation of the posterior probability of the phases, given experimental phase information and expectations about features of the electron-density map. The technique can take advantage of both estimates of electron density in the map and uncertainties or probability distributions for those estimates. For crystals ...

Journal: :Physical review letters 2002
V V Belyi

A generalized version of the Callen-Welton fluctuation-dissipation formula that is nonlocal in space and time is derived. In a nonuniform plasma there appear significant differences between the fluctuations of the electrostatic field and those of the electron density, and the spatial inhomogeneities lead to an asymmetry with respect to the sign inversion of the frequency.

2003
Thomas C. Terwilliger

A method for improving crystallographic phases is presented that is based on the preferential occurrence of certain local patterns of electron density in macromolecular electron-density maps. The method focuses on the relationship between the value of electron density at a point in the map and the pattern of density surrounding this point. Patterns of density that can be superimposed by rotatio...

Journal: :Physical review letters 2010
Y-H Chen S Varma T M Antonsen H M Milchberg

We present direct time- and space-resolved measurements of the electron density of femtosecond laser pulse-induced plasma filaments. The dominant nonlinearity responsible for extended atmospheric filaments is shown to be field-induced rotation of air molecules.

Journal: :Physical review letters 2004
E G Mishchenko A V Shytov B I Halperin

We derive the transport equations for two-dimensional electron systems with Rashba spin-orbit interaction and short-range spin-independent disorder. In the limit of slow spatial variations, we obtain coupled diffusion equations for the electron density and spin. Using these equations we calculate electric-field induced spin accumulation and spin current in a finite-size sample for an arbitrary ...

Journal: :The Journal of chemical physics 2007
Paul W Ayers Agnes Nagy

Stimulated by the difficulty of deriving effective kinetic energy functionals of the electron density, the authors consider using the local kinetic energy as the fundamental descriptor for molecular systems. In this ansatz, the electron density must be expressed as a functional of the local kinetic energy. There are similar results for other quantities, including the local temperature and the K...

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