Local Response Dispersion Research Articles

Importance of van der Waals Descriptions on Accurate Isomerization Energy Calculations of Thiourea Compounds: LCgau-BOP+LRD Method.

We have previously reported that, whereas conventional density functional theory (DFT) functionals have provided poor calculations on the alkane isodesmic reaction energy and isomerization reaction energy of organic molecules that include C, N, and O atoms, our developed long-range corrected (LC)- and LC including Gaussian attenuation (LCgau)-DFT + local response dispersion (LRD) functionals, which can accurately calculate inter- and intramolecular weak interactions, give accurate isomerization energies on these reactions. In this work, we found that B3LYP-D3, LC-ωPBE-D3, and ωB97XD, known for their good descriptions of weak interaction calculations, fail to reproduce the isomerization reaction energies of the molecules that include the S atom, such as methyl-thiourea, ethyl-thiourea, and propyl-thiourea. In contrast, LC- and LCgau-BOP+LRD functionals provide isomerization reaction energies that are very close to those produced by highly accurate wave function methods. These results show that an accurate description of the intramolecular weak interaction between the alkyl group and the S atom, unlike in the case of urea, is significant to reproduce the correct energy of the molecules with an alkyl group and S atom.

Theoretical Study of Extremely Long yet Stable Carbon–Carbon Bonds: Effect of Attractive C···H Interactions and Small Radical Stabilization of Diamondoids

Abstract The origin of the stability of diamondoid dimers containing very long carbon–carbon bonds was examined using density functional theory (DFT) calculations with local response dispersion correction. It has been suggested that noncovalent CH···HC contacts are the probable source of their extraordinary stability as evidenced by dispersion-corrected DFT calculations. In this work, we numerically proved that the small radical stabilization energy, which was achieved through the geometric relaxation of cleaved radicals, led to the high stability of diamondoid dimers compared to other hydrocarbons. The bond energy density analysis showed that the CH···HC contacts are repulsive though the dispersion force somewhat stabilizes the dimer. We further decomposed CH···HC interaction energies to discover strong attractive interaction between Cδ−···Hδ+ intermonomer contacts.

Oxocomplexes of Mo(VI) and W(VI) with 8-hydroxyquinoline-5-sulfonate in solution: structural studies and the effect of the metal ion on the photophysical behaviour.

Multinuclear ((1)H, (13)C, (95)Mo and (183)W) NMR spectroscopy, combined with DFT calculations, provides detailed information on the complexation between the Mo(VI) and W(VI) oxoions and 8-hydroxyquinoline-5-sulfonate (8-HQS) in aqueous solution. Over the concentration region studied, Mo(VI) and W(VI) oxoions form three homologous complexes with 8-HQS in water in the pH range 2-8. Two of these, detected at pH < 6, are mononuclear 1 : 2 (metal : ligand) isomers, with the metal centre (MO2(2+)) coordinated to two 8-HQS ligands. An additional complex, dominant at slightly higher pH values (5-8) for solutions with a 1 : 1 metal : ligand molar ratio, has a binuclear M2O5(2+) centre coordinated to two 8-HQS ligands. The two metal atoms are bridged by three oxygen atoms, two coming from 8-HQS, together with the M-O-M bridge of the bimetallic centre. We show that the long-range exchange corrected BOP functional with local response dispersion (LCBOPLRD), together with explicit solvent molecules, leads to geometries that readily converge to equilibrium structures having realistic bridging O8-HQS-M bonds. Previous attempts to calculate the structures of such binuclear complexes using DFT with the B3LYP functional have failed due to difficulties in treating the weak interaction in these bridged structures. We believe that the LCBOPLRD method may be of more general application in theoretical studies in related binuclear metal complexes. UV/visible absorption and luminescence spectra of all the complexes have also been recorded. The complex between Mo(vi) and 8-HQS is only weakly luminescent, in contrast to what has been observed with this ligand and many other metal ions. We suggest that this is due to the presence of low-lying ligand-to-metal charge transfer (LMCT) states close to the emitting ligand-based level which quench the emission. However, with W(VI), DFT calculations show that the LMCT states are now much higher in energy than the ligand based levels, leading to a marked increase in fluorescence.

Local response dispersion method in periodic systems: Implementation and assessment.

We report the implementation of the local response dispersion (LRD) method in an electronic structure program package aimed at periodic systems and an assessment combined with the Perdew-Burke-Ernzerhof (PBE) functional and its revised version (revPBE). The real-space numerical integration was implemented and performed exploiting the electron distribution given by the plane-wave basis set. The dispersion-corrected density functionals revPBE+LRD was found to be suitable for reproducing energetics, structures, and electron distributions in simple substances, molecular crystals, and physical adsorptions.

Local response dispersion method: A density‐dependent dispersion correction for density functional theory

This review presents theoretical developments and benchmark studies of the local response dispersion (LRD) method. In this scheme, the dispersion correction energy is obtained as the sum of two‐center (atom–atom) and multicenter (atom‐atomic pair and atomic pair‐atomic pair) contributions, which are computed using the electron density and well‐established numerical quadrature. While two‐center interactions are sufficient to reproduce interaction energies at equilibrium geometries, multicenter interactions are important for obtaining the accurate asymptotic behavior. Wide assessments indicate that the LRD method with the long‐range corrected‐B88 exchange and one‐parameter progressive correlation functional is suitable to provide intermolecular interaction energies for various electronic states. In addition, the LRD method reduces errors not only in intermolecular interactions but also in reaction and conformational energies. © 2014 Wiley Periodicals, Inc.

Long‐range corrected density functionals combined with local response dispersion: A promising method for weak interactions

Density functional theory, in general, is considered to underestimate the weak van der Waals type of intermolecular interactions. We optimized parameters of the local response dispersion (LRD) method applied to the long-range corrected exchange-correlation functionals (LC-BOP12+LRD and LCgau-BOP+LRD) on the interaction energy for the complexes in the recently compiled S66 database and found to be comparable with the high-level wave function-based methods reported in Řezáč et al. (J. Chem. Theory Comput. 2011, 7, 2427). Our calculations with the S66 intermolecular complexes at equilibrium geometries suggests that the LC-BOP12+LRD and LCgau-BOP+LRD are well-balanced and lower cost alternatives to the methods reported in the database. Further, test on the S66X8 database (with eight nonequilibrium points) and the HBC6 and NBC10 database shows LC+LRD method with newly optimized parameters is a promising candidate for dealing such weak interactions. Finally, the new parameterized LC+LRD method was tested on X40 benchmark halogenated complexes.

Stochastic Search of Molecular Cluster Interaction Energy Surfaces with Coupled Cluster Quality Prediction. The Phenylacetylene Dimer.

We report a stochastic search methodology on the basis of dispersion-augmented density functional theory (DFT), aimed at finding low energy isomers of the phenylacetylene dimer as well as methane and benzene dimers. Stochastic search of the molecular cluster interaction energy surfaces was carried out with the computationally inexpensive dispersion-augmented, third-order self-consistent charge density functional tight-binding (DFTB3-D) method, and energetically low-lying molecular cluster geometries were identified, including several that had previously been optimized at the MP2/cc-pVTZ level of theory and had single point interaction energies evaluated at the coupled-cluster singles, doubles, and perturbative triples (CCSD(T)) level of theory in the complete basis set limit (Maity, S. et al. Phys. Chem. Chem. Phys 2011, 13, 16706). In addition, the search procedure identifies several additional low-energy isomers that map a reaction path, rotating one monomer through a full 360° relative to the first. We found that binding energies from long-range corrected functional combined with the local response dispersion correction (LC-BOP+LRD) yields binding energies that are within 1 kJ mol(-1) of the CCSD(T)/CBS results for both π-stacked and CH···π structures. In contrast, other functionals and second-order Møller-Plesset perturbation methods favored one binding motif or the other and therefore are not ideal to describe a global potential energy surface.

Benchmark calculations of density functionals for organothiol adsorption on gold surfaces

A comparison of density functionals was carried out for systems consisting of a methanethiyl radical adsorbed on gold in different configurations. PW91, PBE, B3LYP and BLYP were tested in a periodic slab approach. Cluster calculations were carried out so as to compare the above mentioned functionals and many others with CR-CCSD (T) and MRMP2 as references. PW91 and PBE provide close results. Energy surfaces calculated by means of PW91, PBE, M06 and TPSSh are in good agreement with the references. M11 performs dissimilarly from M06, in particular it predicts slightly shorter bond lenghts. BLYP gives rather poor results. The semiempirical scheme of Grimme as parameterized in B97-d and the local response dispersion as parameterized in long range corrected BOP-LRD provide very different estimates of the dispersion energy. Unexpectedly rPBE, B3LYP and CAM-B3LYP perform alike and do not match well with the references, though application of a dispersion energy correction in the Grimme scheme, brings them in a much more favorable position.

Assessment of local response dispersion method for open-shell systems

The performance of the local response dispersion (LRD) method has been assessed for open-shell systems. The LRD method provided reasonable dispersion coefficients and atomic polarizabilities. In open-shell van der Waals complexes, the LRD method was found to improve interaction energies and geometries. Furthermore, the LRD method combined with the long-range corrected exchange functional reproduced the magnetic coupling constants as well as interaction energies of radical dimers. We conclude that this combination has a potential for application to magnetic materials based on organic radicals.

Extension of local response dispersion method to excited-state calculation based on time-dependent density functional theory

We report the extension of the local response dispersion (LRD) method to the excited-state calculation based on time-dependent density functional theory. The difference density matrix, which is usually used for excited-state response properties, enables a state-specific dispersion correction. The numerical assessment proves that interaction energies of exciton-localized molecular complexes and their shifts from the ground state are accurately reproduced by the LRD method. Furthermore, we find that the dispersion correction is important in reproducing binding energies of aromatic excimers, despite the existence of other attractive forces such as exciton delocalization and charge-transfer interaction.

Self‐consistent field treatment and analytical energy gradient of local response dispersion method

AbstractThis study presents the self‐consistent field (SCF) treatment of the local response dispersion (LRD) method. The implementation of SCF involves the modification of the Kohn–Sham Fock matrix by adding the dispersion potential. The derivatives of atomic pseudo‐polarizabilities with respect to the density variables, which are required for evaluating the dispersion potential, are efficiently updated in the SCF procedure. Analytical energy gradient of the LRD method is also developed based on the SCF treatment. Numerical assessments of the present treatment clarified that the SCF effect brings about minor changes in both energy and electronic structure. The computational time, and number of SCF iterations, are essentially unaffected by moving from a non‐self‐consistent implementation to a self‐consistent one. For the geometry optimizations for weakly interacting systems, the inclusion of the LRD energy gradients is shown to be essential for accurately demonstrating the intermolecular geometric parameters. © 2012 Wiley Periodicals, Inc.

An examination of density functional theories on isomerization energy calculations of organic molecules

Long-range corrected (LC) density functional theories (DFTs) were applied to the isomerization energy calculations of organic molecules to make clear why conventional DFTs including B3LYP have given poor isomerization reaction energies. Combining with local response dispersion (LRD) method, we performed LC-DFT calculations for the benchmark set of isomerization reactions. Consequently, we found that LC-DFT + LRD methods give accurate reaction energies equivalent to up-to-date DFTs containing many semi-empirical parameters. This result indicates that long-range exchange and intramolecular dispersion correlation interactions, which have been neglected in conventional DFTs, play prominent roles in isomerization reactions. However, we also found that these interactions are not sufficient to give accurate isomerization energies especially for cyclization reactions. Considering that Gaussian-attenuated LC-DFTs (LCgau-DFTs) give better isomerization reaction energies than LC-DFTs, we suggested that the isomerization energies will be further improved by correcting the short-range part of exchange functionals in DFT with keeping the whole long-range exchange interactions.

Theoretical Investigations on the Photoinduced Phase Transition Mechanism of Tetrathiafulvalene-p-chloranil

The photoinduced phase transition (PIPT) mechanism of tetrathiafulvalene-p-chloranil (TTF-CA) molecular crystal was theoretically investigated using the long-range corrected time-dependent density functional theory (LC-TDDFT) combined with a local response dispersion (LRD) method, which enables us to quantitatively reproduce charge transfer (CT) excitations of van der Waals clusters. By calculating the excitation spectrum and potential energy surface, we found that the PIPT of TTF-CA crystal may proceed through the angle change of the molecular planes. We also found that the CT excitation of one TTF-CA pair helps other neighboring TTF-CA pairs to become excited. Consequently, we theoretically proposed the initial structural change in the neutral-to-ionic PIPT of TTF-CA crystal, which is consistent with experiments.

Local response dispersion method. II. Generalized multicenter interactions

Recently introduced local response dispersion method [T. Sato and H. Nakai, J. Chem. Phys. 131, 224104 (2009)], which is a first-principles alternative to empirical dispersion corrections in density functional theory, is implemented with generalized multicenter interactions involving both atomic and atomic pair polarizabilities. The generalization improves the asymptote of intermolecular interactions, reducing the mean absolute percentage error from about 30% to 6% in the molecular C(6) coefficients of more than 1000 dimers, compared to experimental values. The method is also applied to calculations of potential energy curves of molecules in the S22 database [P. Jurečka et al., Phys. Chem. Chem. Phys. 8, 1985 (2006)]. The calculated potential energy curves are in a good agreement with reliable benchmarks recently published by Molnar et al. [J. Chem. Phys. 131, 065102 (2009)]. These improvements are achieved at the price of increasing complexity in the implementation, but without losing the computational efficiency of the previous two-center (atom-atom) formulation. A set of different truncations of two-center and three- or four-center interactions is shown to be optimal in the cost-performance balance.

Calculations of Alkane Energies Using Long-Range Corrected DFT Combined with Intramolecular van der Waals Correlation

The isodesmic reaction enthalpies of n-alkanes to ethane, which have so far been known to give systematic errors in density functional theory (DFT) calculations, are successfully reproduced using long-range corrected (LC) DFT combined with a local response dispersion (LRD) method, which reveals that the failure of conventional DFT results from the lack of long-range exchange interactions in exchange functionals as well as intramolecular dispersion and medium-range electron correlations in correlation functionals.

Density functional method including weak interactions: Dispersion coefficients based on the local response approximation

A new method to calculate the atom-atom dispersion coefficients in a molecule is proposed for the use in density functional theory with dispersion (DFT-D) correction. The method is based on the local response approximation due to Dobson and Dinte [Phys. Rev. Lett. 76, 1780 (1996)], with modified dielectric model recently proposed by Vydrov and van Voorhis [J. Chem. Phys. 130, 104105 (2009)]. The local response model is used to calculate the distributed multipole polarizabilities of atoms in a molecule, from which the dispersion coefficients are obtained by an explicit frequency integral of the Casimir-Polder type. Thus obtained atomic polarizabilities are also used in the damping function for the short-range singularity. Unlike empirical DFT-D methods, the local response dispersion (LRD) method is able to calculate the dispersion energy from the ground-state electron density only. It is applicable to any geometry, free from physical constants such as van der Waals radii or atomic polarizabilities, and computationally very efficient. The LRD method combined with the long-range corrected DFT functional (LC-BOP) is applied to calculations of S22 weakly bound complex set [Phys. Chem. Chem. Phys. 8, 1985 (2006)]. Binding energies obtained by the LC-BOP+LRD agree remarkably well with ab initio references.