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Hybrid RHF/MP2 geometry optimizations with the effective fragment molecular orbital method.

Christensen AS, Steinmann C, Fedorov DG, Jensen JH - PLoS ONE (2014)

Bottom Line: The approach is applied to the conversion of chorismate to prephenate by Chorismate Mutase, where the substrate is treated at the MP2 level of theory while the rest of the system is treated at the RHF level.MP2 geometry optimization is found to lower the barrier by up to 3.5 kcal/mol compared to RHF optimzations and ONIOM energy refinement and leads to a smoother convergence with respect to the basis set for the reaction profile.For double zeta basis sets the increase in CPU time relative to RHF is roughly a factor of two.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Copenhagen, Copenhagen, Denmark.

ABSTRACT
The frozen domain effective fragment molecular orbital method is extended to allow for the treatment of a single fragment at the MP2 level of theory. The approach is applied to the conversion of chorismate to prephenate by Chorismate Mutase, where the substrate is treated at the MP2 level of theory while the rest of the system is treated at the RHF level. MP2 geometry optimization is found to lower the barrier by up to 3.5 kcal/mol compared to RHF optimzations and ONIOM energy refinement and leads to a smoother convergence with respect to the basis set for the reaction profile. For double zeta basis sets the increase in CPU time relative to RHF is roughly a factor of two.

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Electronic energy versus reaction coordinate for the convesion of chorismate to prephanate in Chorismate Mutase.The three reation paths are calculated using the FDD/EFMO-RHF:MP2 approach with three different basis sets on the reaction complex in the MP2 layer. The 6-31G(d) basis set was used for the RHF layer in all three cases.
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pone-0088800-g004: Electronic energy versus reaction coordinate for the convesion of chorismate to prephanate in Chorismate Mutase.The three reation paths are calculated using the FDD/EFMO-RHF:MP2 approach with three different basis sets on the reaction complex in the MP2 layer. The 6-31G(d) basis set was used for the RHF layer in all three cases.

Mentions: Electronic energy barriers and reaction coordinates for the transition state are given in Table 1 and Fig. 4. We find the electronic energy barrier at the EFMO-RHF/6-31G(d):MP2/6-31G(d) level of theory to be 20.95 kcal/mol. Increasing the size of the basis set on the MP2 fragment decreases the barrier to 19.21 kcal/mol with the cc-pVDZ basis set and 18.34 kcal/mol with the cc-pVTZ basis set.


Hybrid RHF/MP2 geometry optimizations with the effective fragment molecular orbital method.

Christensen AS, Steinmann C, Fedorov DG, Jensen JH - PLoS ONE (2014)

Electronic energy versus reaction coordinate for the convesion of chorismate to prephanate in Chorismate Mutase.The three reation paths are calculated using the FDD/EFMO-RHF:MP2 approach with three different basis sets on the reaction complex in the MP2 layer. The 6-31G(d) basis set was used for the RHF layer in all three cases.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928295&req=5

pone-0088800-g004: Electronic energy versus reaction coordinate for the convesion of chorismate to prephanate in Chorismate Mutase.The three reation paths are calculated using the FDD/EFMO-RHF:MP2 approach with three different basis sets on the reaction complex in the MP2 layer. The 6-31G(d) basis set was used for the RHF layer in all three cases.
Mentions: Electronic energy barriers and reaction coordinates for the transition state are given in Table 1 and Fig. 4. We find the electronic energy barrier at the EFMO-RHF/6-31G(d):MP2/6-31G(d) level of theory to be 20.95 kcal/mol. Increasing the size of the basis set on the MP2 fragment decreases the barrier to 19.21 kcal/mol with the cc-pVDZ basis set and 18.34 kcal/mol with the cc-pVTZ basis set.

Bottom Line: The approach is applied to the conversion of chorismate to prephenate by Chorismate Mutase, where the substrate is treated at the MP2 level of theory while the rest of the system is treated at the RHF level.MP2 geometry optimization is found to lower the barrier by up to 3.5 kcal/mol compared to RHF optimzations and ONIOM energy refinement and leads to a smoother convergence with respect to the basis set for the reaction profile.For double zeta basis sets the increase in CPU time relative to RHF is roughly a factor of two.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Copenhagen, Copenhagen, Denmark.

ABSTRACT
The frozen domain effective fragment molecular orbital method is extended to allow for the treatment of a single fragment at the MP2 level of theory. The approach is applied to the conversion of chorismate to prephenate by Chorismate Mutase, where the substrate is treated at the MP2 level of theory while the rest of the system is treated at the RHF level. MP2 geometry optimization is found to lower the barrier by up to 3.5 kcal/mol compared to RHF optimzations and ONIOM energy refinement and leads to a smoother convergence with respect to the basis set for the reaction profile. For double zeta basis sets the increase in CPU time relative to RHF is roughly a factor of two.

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