Search Results - "Kutzelnigg, Werner"

What I like about Hückel theory by Kutzelnigg, Werner

“…We start with some biographical notes on Erich Hückel, in the context of which we also mention the merits of Otto Schmidt, the inventor of the free‐electron…”
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Which masses are vibrating or rotating in a molecule? by Kutzelnigg, Werner

“…The traditional formulation of a molecular wave function describing the motion of the electrons and the nuclei in terms of the Born hierarchy does not allow us…”
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How many-body perturbation theory (MBPT) has changed quantum chemistry by Kutzelnigg, Werner

“…The history of many‐body perturbation theory (MBPT) and its impact on Quantum Chemistry is reviewed, starting with Brueckner's conjecture of a linked‐cluster…”
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Relativistic corrections to the partial wave expansion of two-electron atoms by Kutzelnigg, Werner

“…The asymptotic behavior of the partial wave expansion (or the CI expansion in terms of AOs with angular quantum number l) of the leading relativistic…”
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Comparison of restricted, unrestricted, inverse, and dual kinetic balances for four-component relativistic calculations by Sun, Qiming, Liu, Wenjian, Kutzelnigg, Werner

“…Various kinetic balances for constructing appropriate basis sets in four-component relativistic calculations are examined in great detail. These include the…”
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Quasirelativistic theory I. Theory in terms of a quasi-relativistic operator by Kutzelnigg, Werner, Liu, Wenjian

“…In this first part of a general analysis of a quasi-relativistic theory, i.e. a relativistic theory for electrons only, the transformation of the Dirac…”
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Relativistic one-electron Hamiltonians `for electrons only' and the variational treatment of the Dirac equation by Kutzelnigg, Werner

“…A relation χ= Xϕ between the upper and lower components of the Dirac spinor ψ=( ϕ, χ), with X satisfying a nonlinear operator equation, guarantees that the…”
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Solved and unsolved problems in relativistic quantum chemistry by Kutzelnigg, Werner

“…The graphical abstract represents the Dirac-Coulomb Hamiltonian in Fock space in a diagrammatic notation. A line (vertical or slanted) with an upgoing arrow…”
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Non-adiabatic theory in terms of a single potential energy surface. The vibration–rotation levels of and by Jaquet, Ralph, Kutzelnigg, Werner

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Explicitly correlated potential energy surface of , including relativistic and adiabatic corrections by Kutzelnigg, Werner, Jaquet, Ralph

“…ion, two…”
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Separation of strong (bond-breaking) from weak (dynamical) correlation by Kutzelnigg, Werner

“…We start from a coupled cluster ansatz, i.e. an exponential form e(S+T) for the wave operator. We decompose the cluster amplitude (S+T) into a part S which…”
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Expansion of a wave function in a Gaussian basis. I. Local versus global approximation by Kutzelnigg, Werner

“…The expansion of the ground state wave function ψ(r) of hydrogen‐like ions in a Gaussian basis is derived from a discretization of a Gaussian integral…”
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Direct determination of the cumulants of the reduced density matrices by Kutzelnigg, Werner, Mukherjee, Debashis

“…Unlike the reduced k-body density matrices, the k-body cumulants generated from them are extensive entities. We formulate a theory directly in terms of these…”
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An Alternative Hierarchy of Electron Correlation beyond the Electron Pair Approximation by Kutzelnigg, Werner

“…Starting from the Nakatsuji theorem, a hierarchy of approximations is considered that begins with traditional coupled cluster theory with singles and doubles…”
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Density functional theory in terms of a Legendre transformation for beginners by Kutzelnigg, Werner

“…The derivation of the Hohenberg–Kohn (HK) theorem by means of a simplified version of Lieb's Legendre transformation is presented, with the stress on…”
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Björn O. Roos (1937-2010) by Kutzelnigg, Werner

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The principle-quantum-number (and the radial-quantum-number) expansion of the correlation energy of two-electron atoms by Kutzelnigg, Werner

“…The second-order correlation energy of two-electron ions is studied in terms of an expansion in minimal approximations to the first-order natural orbitals…”
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Non-adiabatic theory in terms of a single potential energy surface. The vibration–rotation levels of H 2 + and D 2 by Jaquet, Ralph, Kutzelnigg, Werner

“…The traditional formulation of a molecular wave function describing the motion of the electrons and the nuclei, in terms of the Born hierarchy, does not allow…”
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Error analysis and improvements of coupled-cluster theory by Kutzelnigg, Werner

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The adiabatic approximation I. The physical background of the Born-Handy ansatz by KUTZELNIGG, WERNER

“…There are two current ways to evaluate the adiabatic corrections to a potential energy hypersurface: firstly a rigorous way in which one starts with the…”
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