Published June 1983
| Version v1
Journal article
Common approximations for density operators may lead to imaginary entropy
Creators
- 1. Zurich Univ. (Switzerland). Inst. of Physical Chemistry
- 2. Rio de Janeiro Univ. (Brazil). Inst. de Fisica
Description
The meaning and validity of usual second order approximations for density operators are illustrated with the help of a simple exactly soluble two-level model in which all relevant quantities can easily be controlled. This leads to exact upper bound error estimates which help to select more precisely permissible correlation times as frequently introduced if stochastic potentials are present. A final consideration of information entropy reveals clearly the limitations of this kind of approximation procedures. (Author)
Abstract (Portuguese)
Esclarecem-se o significado e a validade da aproximacao usual de segunda ordem para operadores de densidade com a ajuda de um modelo simples a duas dimensoes, resolvivel exatamente, em que todas as quantidades relevantes podem ser facilmente controladas. Isso permite uma avaliacao exata do limite maximo de erro, o que nos ajuda a selecionar mais precisamente os tempos de correlacao permissiveis, que sao frequentemente introduzidos se potenciais estocasticos estao presentes. Uma consideracao final sobre a informacao entropia revela claramente as limitacoes desse tipo de aproximacao. (Autor)Additional details
Publishing Information
- Journal Title
- Rev. Bras. Fis.
- Journal Volume
- 13
- Journal Issue
- 2
- Series
- Rev. Bras. Fis.
- Journal Page Range
- 294-302
- ISSN
- 0374-4922
INIS
- Country of Publication
- Brazil
- Country of Input or Organization
- Brazil
- INIS RN
- 15054108
- Subject category
- S71: CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS;
- Descriptors DEI
- ANALYTICAL SOLUTION; DENSITY MATRIX; ENTROPY; EQUATIONS OF MOTION; HAMILTONIANS; TWO-DIMENSIONAL CALCULATIONS
- Descriptors DEC
- DIFFERENTIAL EQUATIONS; EQUATIONS; MATHEMATICAL OPERATORS; MATRICES; PARTIAL DIFFERENTIAL EQUATIONS; PHYSICAL PROPERTIES; QUANTUM OPERATORS; THERMODYNAMIC PROPERTIES