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Full-Text Articles in Physics
Quasidegenerate Variational Perturbation Theory And The Calculation Of First‐Order Properties From Variational Perturbation Theory Wave Functions, Robert J. Cave, Ernest R. Davidson
Quasidegenerate Variational Perturbation Theory And The Calculation Of First‐Order Properties From Variational Perturbation Theory Wave Functions, Robert J. Cave, Ernest R. Davidson
All HMC Faculty Publications and Research
In previous work on the treatment of correlation in molecular systems we have applied a multireference version of second‐order Hylleraas variational perturbation theory. The choice made for the partitioning of H treated the interactions between the correlating functions to infinite order and gave the corrections to the wave function to first order. The method was shown to be accurate in many cases, but became less so when near degeneracies occurred between the reference energy and other eigenvalues of H0. In this article we introduce an effective Hamiltonian method that is analogous to variational perturbation theory, but which is significantly more …
Hylleraas Variational Perturbation Theory: Application To Correlation Problems In Molecular Systems, Robert J. Cave, Ernest R. Davidson
Hylleraas Variational Perturbation Theory: Application To Correlation Problems In Molecular Systems, Robert J. Cave, Ernest R. Davidson
All HMC Faculty Publications and Research
Hylleraas variational perturbation theory is applied through second order in energy to estimate the correlation energy in several molecular systems. The specific choices for H0 and V which are made lead to equations nearly identical to the multireference linearized coupled‐cluster method of Laidig and Bartlett. The results obtained are in virtually exact agreement where comparisons have been made. Results from test calculations are presented for BeH2, CH2, and C2H4. In addition, the utility of perturbation theory for selecting correlating configurations is examined. This procedure is found to be quite accurate while …
Effects Of Chemical And Magnetic Disorder In Fe0.50mn0.50, Duane D. Johnson, F. J. Pinski, G. M. Stocks
Effects Of Chemical And Magnetic Disorder In Fe0.50mn0.50, Duane D. Johnson, F. J. Pinski, G. M. Stocks
Duane D. Johnson
We present the results of first‐principles calculations of the total energy and spin‐polarized electronic structure of disordered fcc Fe0.50Mn0.50. These self‐consistent calculations were performed using the Korringa–Kohn–Rostoker method and the coherent‐potential approximation (KKR‐CPA), using the local‐spin‐density approximation to treat exchange and correlation. We use a lattice constant of a=6.80 a.u.; information about stability can be inferred from calculated pressure and energy. The moments on the Fe and Mn sites are large but antiparallel to each other, resulting in a small net magnetization. A comparison of the electronic structure is made for fcc Fe, Mn, and FeMn in both the ferromagnetic …