Localized orbitals for molecular calculations
نویسندگان
چکیده
We present an overview of the existing localization algorithms which have been or are being used to perform quantum chemical molecular calculations that take into account electronic correlation effects. The natural distinction between intrinsic and extrinsic localization methods is explained and developed. The advantages and drawbacks of specific methods are discussed in terms of CPU time required to obtain the (in most cases) almost identical localized molecular orbitals. Finally, we show using a specific example of a second order multireference perturbational calculation, the enormous gain in computer time that the use of localized molecular orbitals can bring. We also show explicitly the "concentration" of second order Miiller-Plesset correlation energy into a much smaller perturbed space. RESUMEN.Se presenta una revisión de los métodos de localización de orbitales usados para realizar cálculos moleculares químico-cuánticos que toman en cuenta efectos de correlación electrónica. La distinción natural entre métodos de localización intrínsecos y extrínsecos es explicada y desarrollada en detalle. Las ventajas y desventajas de métodos específicos son discutidas comparativamente en términos del tiempo de CPU requerido para obtener, en la mayoría de los casos, los orbitales localizados prácticamente idénticos. Finalmente mostramos, usando un ejemplo específico de un cálculo perturbativo multirreferencial de segundo orden, la enorme ganancia en tiempo de máquina que el uso adecuado de orbitales localizados puede proporcionar respecto al uso de orbitales canónicos SCF o CAS-SCF. También se hace explícita la gran "concentración" de energía de correlación de segundo orden M611er-Plessct en un número mucho menor de determinantes.
منابع مشابه
Topological Localized Molecular Orbitals of Hiickel and Mobius Annulenes*
A localization method in the framework of Ruckel MO theory which relies only on molecular topology, and which can be regarded to as the topological version of well established localization criteria, has been applied to the series of (n)annulenes. The calculations have been effected for both Ruckel and Mobius topologies, and several aspects of the resulting localized orbitals (homogeneity, equiv...
متن کاملEfficient construction of nonorthogonal localized molecular orbitals in large systems.
Localized molecular orbitals (LMOs) are much more compact representations of electronic degrees of freedom than canonical molecular orbitals (CMOs). The most compact representation is provided by nonorthogonal localized molecular orbitals (NOLMOs), which are linearly independent but are not orthogonal. Both LMOs and NOLMOs are thus useful for linear-scaling calculations of electronic structures...
متن کاملParallel, linear-scaling building-block and embedding method based on localized orbitals and orbital-specific basis sets.
We present a linear scaling method for the energy minimization step of semiempirical and first-principles Hartree-Fock and Kohn-Sham calculations. It is based on the self-consistent calculation of the optimum localized orbitals of any localization method of choice and on the use of orbital-specific basis sets. The full set of localized orbitals of a large molecule is seen as an orbital mosaic w...
متن کاملEnergy Decomposition Analysis Based on Absolutely Localized Molecular Orbitals for Large-Scale Density Functional Theory Calculations in Drug Design.
We report the development and implementation of an energy decomposition analysis (EDA) scheme in the ONETEP linear-scaling electronic structure package. Our approach is hybrid as it combines the localized molecular orbital EDA (Su, P.; Li, H. J. Chem. Phys., 2009, 131, 014102) and the absolutely localized molecular orbital EDA (Khaliullin, R. Z.; et al. J. Phys. Chem. A, 2007, 111, 8753-8765) t...
متن کاملPipek-Mezey Orbital Localization Using Various Partial Charge Estimates.
The Pipek-Mezey scheme for generating chemically intuitive, localized molecular orbitals is generalized to incorporate various ways of estimating the atomic charges, instead of the ill-defined Mulliken charges used in the original formulation, or Löwdin charges, which have also been used. Calculations based on Bader, Becke, Voronoi, Hirshfeld, and Stockholder partial charges, as well as intrins...
متن کامل