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arXiv · 1008.4606

The optimized Rayleigh-Ritz scheme for determining the quantum-mechanical spectrum

Przemyslaw Koscik·Anna Okopinska
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Abstract

The convergence of the Rayleigh-Ritz method with nonlinear parameters optimized through minimization of the trace of the truncated matrix is demonstrated by a comparison with analytically known eigenstates of various quasi-solvable systems. We show that the basis of the harmonic oscillator eigenfunctions with optimized frequency ? enables determination of boundstate energies of one-dimensional oscillators to an arbitrary accuracy, even in the case of highly anharmonic multi-well potentials. The same is true in the spherically symmetric case of V (r) = {\omega}2r2 2 + {\lambda}rk, if k > 0. For spiked oscillators with k < -1, the basis of the pseudoharmonic oscillator eigenfunctions with two parameters ? and {\gamma} is more suitable, and optimization of the latter appears crucial for a precise determination of the spectrum.

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Przemyslaw Koscik, Anna Okopinska. 2010-08-26. The optimized Rayleigh-Ritz scheme for determining the quantum-mechanical spectrum. https://doi.org/10.1088/1751-8113/40/35/009

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