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Applications and assessment of QM:QM electronic embedding using generalized asymmetric Mulliken atomic charges
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10.1063/1.2976570
/content/aip/journal/jcp/129/14/10.1063/1.2976570
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/14/10.1063/1.2976570

Figures

Image of FIG. 1.
FIG. 1.

Models used for the ONIOM QM:QM EE method—the high-level region is denoted as ball and stick representation and low-level region as tube rendering. (a) Proton transfer in a complex. (b) Removal of water from a complex.

Image of FIG. 2.
FIG. 2.

PESs for the proton transfer between two water molecules in a complex at different model chemistries; high-level target, low-level, ONIOM mechanical embedding (ME) and ONIOM point charge embedding (PT). (a) , (b) , and (c) . In (a), the PES calculated by ONIOM point charge embedding almost coincides with the high-level target PES.

Image of FIG. 3.
FIG. 3.

PESs for the removal of water molecule from a complex at the model chemistry. Note the catastrophic failure of the ONIOM-ME method with increasing Zn–O distance.

Image of FIG. 4.
FIG. 4.

PESs for the removal of from the complex in the gas phase. The squares indicate the surface that is the high-level target, the circles indicate regular Mulliken point charge embedding at the level, the triangles show point charge embedding with 70% of the electron overlap population on Zn and 30% on N of the imidazole ligands, and the stars indicate the case with 30% on Zn and 70% on N.

Image of FIG. 5.
FIG. 5.

The three ways [(A)–(C)] used to divide the entire hydroxylated spherosiloxane cluster into two layers: The high-level region is indicated as ball and stick representation and the low-level region as tube rendering.

Tables

Generic image for table
Table I.

Modified Mulliken charge analysis for orthosilicic acid with 75% and 100% of the electron overlap populations assigned to oxygen in a O–Si bond. Also shown are the regular Mulliken analysis (50% of the electron populations assigned to each O and Si), NBO, ESP derived charges, and Bader charges. The calculations are at the B3LYP/6-31G level.

Generic image for table
Table II.

Modified Mulliken charge analysis for the siloxide anion with 75% and 100% of the electron overlap populations assigned to oxygen in a O–Si bond. Also shown are the regular Mulliken analysis (50% of the electron populations assigned to each O and Si), NBO, ESP derived charges, and Bader charges. The calculations are at the B3LYP/6-31G level.

Generic image for table
Table III.

Proton affinity (kcal/mol) of the spherosiloxane cube anion calculated by ONIOM-ME and ONIOM-EE. Also included for comparison are the target high-level and low-level methods. The mean absolute deviations of the ONIOM-ME and ONIOM-EE methods are 5.3 and , respectively.

Generic image for table
Table IV.

Errors in the proton affinity of the spherosiloxane cube anion (model A) calculated by ONIOM-ME and ONIOM-EE with regular Mulliken point charges (50-50) and asymmetric Mulliken charges obtained by dividing the electron overlap populations between O and Si unequally as 60% on O, 40% on Si and 70% on O, 30% on Si.

Generic image for table
Table V.

Geometrical parameters for the hydroxylated spherosiloxane cube of symmetry, (model A) for various model chemistry combinations including ONIOM-ME and ONIOM-EE.

Generic image for table
Table VI.

Geometrical parameters for the deprotonated hydroxylated spherosiloxane anion of symmetry, (model A) for various model chemistry combinations including ONIOM-ME and ONIOM-EE.

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/content/aip/journal/jcp/129/14/10.1063/1.2976570
2008-10-10
2014-04-17
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Applications and assessment of QM:QM electronic embedding using generalized asymmetric Mulliken atomic charges
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/14/10.1063/1.2976570
10.1063/1.2976570
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