45 citations · 92 across the 4 of their papers we have counts for
6 papers
Variational Approach to Hydrogen Atom in Uniform Magnetic Field of Arbitrary Strength
M. Bachmann, H. Kleinert, A. Pelster
Extending the Feynman-Kleinert variational approach, we calculate the temperature-dependent effective classical potential governing the quantum statistics of a hydrogen atom in a u…
Recursive Graphical Construction of Feynman Diagrams and Their Multiplicities in phi^4- and in phi^2A-Theory
Hagen Kleinert, Axel Pelster, Boris Kastening +1
The free energy of a field theory can be considered as a functional of the free correlation function. As such it obeys a nonlinear functional differential equation which can be tur…
Recursive Graphical Construction for Feynman Diagrams of Quantum Electrodynamics
M. Bachmann, H. Kleinert, A. Pelster
We present a method for a recursive graphical construction of Feynman diagrams with their correct multiplicities in quantum electrodynamics. The method is first applied to find all…
Strong-Coupling Calculation of Fluctuation Pressure of a Membrane Between Walls
M. Bachmann, H. Kleinert, A. Pelster
We calculate analytically the proportionality constant in the pressure law of a membrane between parallel walls from the strong-coupling limit of variational perturbation theory up…
Generating Functionals for Harmonic Expectation Values of Paths with Fixed End Points. Feynman Diagrams for Nonpolynomial Interactions
Hagen Kleinert, Axel Pelster, Michael Bachmann
We introduce a general class of generating functionals for the calculation of quantum-mechanical expectation values of arbitrary functionals of fluctuating paths with fixed end poi…
Variational Perturbation Theory for Density Matrices
M. Bachmann, H. Kleinert, A. Pelster
We develop convergent variational perturbation theory for quantum statistical density matrices. The theory is applicable to polynomial as well as nonpolynomial interactions. Illust…