Long-range corrected density functional calculations of chemical reactions: Redetermination of parameter

Abstract

Chemical reaction calculations were carried out using the long-range correction (LC) scheme, which improves long-range exchange effects in density functional theory (DFT) [J. Chem. Phys. 115, 3540 (2001); 120, 8425 (2004)]. A new determination of the LC scheme parameter mu was made by a root mean square fit of the percent error in calculated atomization energies. As a result, the parameter mu was optimized as 0.47, which is higher than the previous one (mu=0.33). Using this new parameter mu, LC-DFT was firstly applied to geometry optimizations of the G2 benchmark set molecules. Consequently, this new LC-DFT gave more accurate bond lengths and bond angles than previous LC-DFT and hybrid B3LYP results. Following this result, the authors calculated reaction barrier height energies of benchmark reaction sets, which have been underestimated in conventional DFT calculations. Calculated results showed that LC-DFT provided much more accurate barrier height energies with errors less than half those of previous LC-DFT and B3LYP studies. To test the general validity of the new LC-DFT, the authors finally calculated reaction enthalpies. As a result, they found that the LC scheme using the new mu clearly improved the accuracy of calculated enthalpies. The authors therefore conclude that the insufficient inclusion of long-range exchange effects is responsible for the underestimation of reaction barriers in DFT calculations and that LC-DFT using the new parameter is a powerful tool for theoretically investigating chemical reactions.

Tuning Range-Separated Density Functional Theory for Photocatalytic Water Splitting Systems

“…54,55 The value 0.33 bohr −1 was determined by a least square fit to empirical data for first-to third-row atoms 52 and later refined to 0.47 bohr −1 for larger sets of small molecules. 53 (for other test sets, see also refs. 49,50,56,57 ) However, it is clear that for molecules, which have not been part of the training sets, a more accurate description will be provided by choosing a system-dependent ω.…”

“…Such an approach eliminates the spurious behaviour because the exact exchange has the correct asymptotic character and cancels the selfinteraction exactly. [46][47][48][49][50][51] Certain standard values for the range-separation parameter ω have been established in refs 52,53 and they are used like universal constants in popular quantum chemical programs. 54,55 The value 0.33 bohr −1 was determined by a least square fit to empirical data for first-to third-row atoms 52 and later refined to 0.47 bohr −1 for larger sets of small molecules.…”

“…20,35,40,42,50,52,53,[59][60][61][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82] The accuracy of optimally tuned range-separated functionals was critically tested in ref 61 for basis set variation as well as prediction of relative energies of spin states, binding energies, and the form of potential energy surfaces.…”

Calculating the Fluorescence of 5-Hydroxytryptophan in Proteins

“…The first is a gradual switchover of the exchange integrals from that calculated by the density functional to 100% Hartree-Fock exchange. 35,36 This is applicable to many existing functionals and gives good results, where standard functionals fail dramatically, such as for the π-stacked adenine dimer. 37 The second approach is to have a corrected functional, whereby the correction is part of the definition of that functional.…”

Structural and Electronic Properties of Polyacetylene and Polyyne from Hybrid and Coulomb-Attenuated Density Functionals

“…Functionals developed using an exchange partitioning provide improved performance over standard hybrid functionals for a variety of properties, [9][10][11][12] such as excited states, 10,13-19 electric-field-induced second harmonic generation, 20 nonlinear optical properties, 21 optical rotation, 22 and reaction barriers. 10, 23 Our own work has highlighted that CA functionals offer an improved description of excited states and barriers while maintaining competitive performance for other thermochemical and geometrical properties. 10 An area that may benefit from the application of CA functionals is the study of polymeric chains; see refs [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] for recent relevant studies.…”