Kozuch, S.; Gruzman, D.; Martin, J. M. L. "DSD-BLYP: A General Purpose Double Hybrid Density Functional Including Spin Component Scaling and Dispersion Correction,"

Kozuch, S.; Martin, J. M. L. "DSD-PBEP86: in search of the best double-hybrid DFT with spin-component scaled MP2 and dispersion corrections,"

Contributed by Steven Bachrach.

Reposted from Computational Organic Chemistry with permission

*J. Phys. Chem. C*, 2010, 114, 20801-20808Kozuch, S.; Martin, J. M. L. "DSD-PBEP86: in search of the best double-hybrid DFT with spin-component scaled MP2 and dispersion corrections,"

*Phys. Chem. Chem. Phys.*2011, 13, 20104-20107Contributed by Steven Bachrach.

Reposted from Computational Organic Chemistry with permission

I just returned from the Southwest Theoretical Chemistry Conference held at Texas A&M University. My thanks again to Steven Wheeler for the invitation to speak at the meeting and for putting together a very fine program and conference.

Among the many interesting talks was one by Sebastian Kozuch who reported on an interesting double hybrid methodology.

^{1,2}Working with Jan Martin, they defined a procedure that Kozuch referred to as “putting Stefan Grimme into a blender”. They extend the double hybrid concept first suggested by Grimme that adds on an MP2-like correction functional. Kozuch and Martin substitute a spin-component scaled MP2 (SCS-MP2) model for the original MP2 correction. SCS-MP2 was also proposed by Grimme. Lastly, they add on a dispersion correction, an idea championed by Grimme too. The exchange-correlation term is defined as*E*=

_{XC}*c*+ (1 –

_{X}E_{X}^{DFT}*c*)

_{x}*E*+

_{x}^{HF}*c*+

_{C}E_{C}^{DFT}*c*+

_{O}E_{O}^{MP2}*c*+

_{S}E_{S}^{MP2}*s*

_{6}E_{D}
where

*c*is the coefficient for the amount of DFT exchange,_{X}*c*the amount of DFT correlation,_{C}*c*and_{C}*c*the amount of opposite- and same-spin MP2, and_{S}*s*the amount of dispersion. They name this procedure_{6}**DSD-DFT**for**D**ispersion corrected,**S**pin-component scaled**D**ouble hybrid**DFT**.
In their second paper on this subject, they propose the use of the PBEP86 functional for the DFT components.

^{2}Benchmarking against a variety of standard databases, including kinetic data, thermodynamic data, along with inorganic and weakly interacting systems, this method delivers the lowest mean error among a small set of functionals. Kozuch reported at the conference on a number of other combinations and should have a publication soon suggesting an even better method. Importantly, these DSD-DFT computations can be run with most major quantum codes including*Orca*,*Molpro*,*Q-Chem*and*Gaussian*(with a series of IOP specifications).
While double hybrid methods don’t have quite the performance capabilities of regular DFT, density fitting procedures offer the possibility of a significant reduction in computational time. These DSD-DFT methods are certainly worthy of fuller explorations.

### References

(1) Kozuch, S.; Gruzman, D.; Martin, J. M. L. "DSD-BLYP: A General Purpose Double Hybrid Density Functional Including Spin Component Scaling and Dispersion Correction,"

DOI: 10.1021/jp1070852

*J. Phys. Chem. C*,**2010**,*114*, 20801-20808,DOI: 10.1021/jp1070852

(2) Kozuch, S.; Martin, J. M. L. "DSD-PBEP86: in search of the best double-hybrid DFT with spin-component scaled MP2 and dispersion corrections,"

*Phys. Chem. Chem. Phys.***2011**,*13*, 20104-20107, DOI: 10.1039/C1CP22592H