A significantly impoved method of construction

of the Rayleigh-Schrödinger perturbation series.

•  

• In Int. J. Mod. Phys. A 12 (1997) 299 - 304

• an asymmetric version of perturbation method assumes that

• a Hamiltonian H = H(g), g~0 of physical interest is

  • weakly parameter-dependent

  • "too distant" from any easily diagonalized model

  • tridiagonal (e.g., represented in a Lanczos bi-orthogonal basis)

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• recent proceedings

• may be also consulted for detailed account of the

• highly schematic V(x) = polynomial(x)/polynomial(x) .