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- Semi-empirical_quantum_chemistry_method abstract "Semi-empirical quantum chemistry methods are based on the Hartree–Fock formalism, but make many approximations and obtain some parameters from empirical data. They are very important in computational chemistry for treating large molecules where the full Hartree–Fock method without the approximations is too expensive. The use of empirical parameters appears to allow some inclusion of electron correlation effects into the methods.Within the framework of Hartree–Fock calculations, some pieces of information (such as two-electron integrals) are sometimes approximated or completely omitted. In order to correct for this loss, semi-empirical methods are parametrized, that is their results are fitted by a set of parameters, normally in such a way as to produce results that best agree with experimental data, but sometimes to agree with ab initio results.Semi-empirical methods follow what are often called empirical methods where the two-electron part of the Hamiltonian is not explicitly included. For π-electron systems, this was the Hückel method proposed by Erich Hückel. For all valence electron systems, the extended Hückel method was proposed by Roald Hoffmann.Semi-empirical calculations are much faster than their ab initio counterparts, mostly due to the use of the zero differential overlap approximation. Their results, however, can be very wrong if the molecule being computed is not similar enough to the molecules in the database used to parametrize the method.Semi-empirical calculations have been most successful in the description of organic chemistry, where only a few elements are used extensively and molecules are of moderate size. However, semi-empirical methods were also applied to solids and nanostructures but with different parameterization.Empirical research is a way of gaining knowledge by means of direct and indirect observation or experience. As with empirical methods, we can distinguish methods that are: restricted to π-electrons. These method exist for the calculation of electronically excited states of polyenes, both cyclic and linear. These methods, such as the Pariser–Parr–Pople method (PPP), can provide good estimates of the π-electronic excited states, when parameterized well. Indeed, for many years, the PPP method outperformed ab initio excited state calculations.or those: restricted to all valence electrons. These methods can be grouped into several groups: Methods such as CNDO/2, INDO and NDDO that were introduced by John Pople. The implementations aimed to fit, not experiment, but ab initio minimum basis set results. These methods are now rarely used but the methodology is often the basis of later methods. Methods that are in the MOPAC, AMPAC, and/or SPARTAN computer programs originally from the group of Michael Dewar. These are MINDO, MNDO, AM1, PM3, RM1 , PM6 and SAM1. Here the objective is to use parameters to fit experimental heats of formation, dipole moments, ionization potentials, and geometries. Methods whose primary aim is to predict the geometries of coordination compounds, such as Sparkle/AM1, available for lanthanide complexes. Methods whose primary aim is to calculate excited states and hence predict electronic spectra. These include ZINDO and SINDO.the latter being by far the largest group of methods.".
- Semi-empirical_quantum_chemistry_method wikiPageExternalLink www.sparkle.pro.br.
- Semi-empirical_quantum_chemistry_method wikiPageExternalLink www.rm1.sparkle.pro.br.
- Semi-empirical_quantum_chemistry_method wikiPageID "4682498".
- Semi-empirical_quantum_chemistry_method wikiPageLength "7463".
- Semi-empirical_quantum_chemistry_method wikiPageOutDegree "29".
- Semi-empirical_quantum_chemistry_method wikiPageRevisionID "704840785".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink AMPAC.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Ab_initio_quantum_chemistry_methods.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Austin_Model_1.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink 2.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Category:Semiempirical_quantum_chemistry_methods.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Computational_chemistry.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Electronic_correlation.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Erich_Hückel.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Extended_Hückel_method.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Hamiltonian_(quantum_mechanics).
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Hartree–Fock_method.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Hückel_method.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink INDO.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink John_Pople.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink List_of_quantum_chemistry_and_solid-state_physics_software.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink MINDO.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink MNDO.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink MOPAC.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Michael_J._S._Dewar.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink NDDO.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink PM3_(chemistry).
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Pariser–Parr–Pople_method.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Quantum_chemistry.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Roald_Hoffmann.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink SAM1.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink SINDO.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Spartan_(software).
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink ZINDO.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLink Zero_differential_overlap.
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText ":Semi-empirical quantum chemistry method".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "Semi-emp.".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "Semi-empirical calculations".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "Semi-empirical methods".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "Semi-empirical quantum chemistry method".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "Semi-empirical".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "Semiempirical methods".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "semi-empirical methods".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "semi-empirical quantum chemistry method".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "semi-empirical".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "semiempirical method".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "semiempirical methods".
- Semi-empirical_quantum_chemistry_method wikiPageWikiLinkText "semiempirical".
- Semi-empirical_quantum_chemistry_method wikiPageUsesTemplate Template:Electronic_structure_methods.
- Semi-empirical_quantum_chemistry_method wikiPageUsesTemplate Template:Reflist.
- Semi-empirical_quantum_chemistry_method subject Category:Semiempirical_quantum_chemistry_methods.
- Semi-empirical_quantum_chemistry_method type Method.
- Semi-empirical_quantum_chemistry_method type Redirect.
- Semi-empirical_quantum_chemistry_method type Concept.
- Semi-empirical_quantum_chemistry_method comment "Semi-empirical quantum chemistry methods are based on the Hartree–Fock formalism, but make many approximations and obtain some parameters from empirical data. They are very important in computational chemistry for treating large molecules where the full Hartree–Fock method without the approximations is too expensive.".
- Semi-empirical_quantum_chemistry_method label "Semi-empirical quantum chemistry method".
- Semi-empirical_quantum_chemistry_method sameAs Q3097812.
- Semi-empirical_quantum_chemistry_method sameAs Méthode_quantique_semi-empirique.
- Semi-empirical_quantum_chemistry_method sameAs 半経験的分子軌道法.
- Semi-empirical_quantum_chemistry_method sameAs Metody_półempiryczne.
- Semi-empirical_quantum_chemistry_method sameAs m.0ch2h8.
- Semi-empirical_quantum_chemistry_method sameAs Semiempiriska_metoder_inom_kvantkemi.
- Semi-empirical_quantum_chemistry_method sameAs Напівемпіричні_методи.
- Semi-empirical_quantum_chemistry_method sameAs Q3097812.
- Semi-empirical_quantum_chemistry_method wasDerivedFrom Semi-empirical_quantum_chemistry_method?oldid=704840785.
- Semi-empirical_quantum_chemistry_method isPrimaryTopicOf Semi-empirical_quantum_chemistry_method.