scholarly journals The effect of electronic excitation on London dispersion

2018 ◽  
Vol 96 (7) ◽  
pp. 730-737 ◽  
Author(s):  
Xibo Feng ◽  
Alberto Otero-de-la-Roza ◽  
Erin R. Johnson
Keyword(s):  
Density Functional ◽  
Electronic Excitation ◽  
Organic Dyes ◽  
Dispersion Model ◽  
Dispersion Energy ◽  
Dispersion Coefficients ◽  
Light Emitting ◽  
Molecular Dispersion ◽  
London Dispersion

Atomic and molecular dispersion coefficients can now be calculated routinely using density-functional theory. In this work, we present the first determination of how electronic excitation affects molecular C6 London dispersion coefficients from the exchange-hole dipole moment (XDM) dispersion model. Excited states are typically found to have larger dispersion coefficients than the corresponding ground states, due to their more diffuse electron densities. A particular focus is both intramolecular and intermolecular charge-transfer excitations, which have high absorbance intensities and are important in organic dyes, light-emitting diodes, and photovoltaics. In these classes of molecules, the increase in C6 for the electron-accepting moiety is largely offset by a decrease in C6 for the electron-donating moiety. As a result, the change in dispersion energy for a chromophore interacting with neighbouring molecules in the condensed phase is minimal.

scholarly journals A Generally Applicable Atomic-Charge Dependent London Dispersion Correction Scheme

2018 ◽  
Author(s):  
Eike Caldeweyher ◽  
Sebastian Ehlert ◽  
Andreas Hansen ◽  
Hagen Neugebauer ◽  
Sebastian Spicher ◽  
...  
Keyword(s):  
Density Functional ◽  
Dispersion Model ◽  
Atomic Charge ◽  
Body Part ◽  
Dispersion Interactions ◽  
Dispersion Energy ◽  
Dispersion Coefficients ◽  
Charge Dependence ◽  
London Dispersion ◽  
Dynamic Polarizabilities

<div>The so-called D4 model is presented for the accurate computation of London dispersion interactions in density functional theory approximations (DFT-D4) and generally for atomistic modelling methods. In this successor to the DFT-D3 model, the atomic coordination-dependent dipole polarizabilities are scaled based on atomic partial charges which can be taken from various sources. For this purpose, a new charge-dependent parameter-economic scaling function is designed. Classical charges are obtained from an atomic electronegativity equilibration procedure for which efficient analytical derivatives with respect to nuclear positions are developed. A numerical Casimir-Polder integration of the atom-in-molecule dynamic polarizabilities then yields charge- and geometry-dependent dipole-dipole dispersion coefficients. Similar to the D3 model, the dynamic polarizabilities are pre-computed by time-dependent DFT and all elements up to radon (Z = 86) are covered. The two-body dispersion energy expression has the usual sum-over-atom-pairs form and includes dipole-dipole, as well as dipole-quadrupole interactions. For a benchmark set of 1225 molecular dipole-dipole dispersion coefficients, the D4 model achieves an unprecedented accuracy with a mean relative deviation of 3.9% compared to 4.7% for D3. In addition to the two-body part, three-body effects are described by an Axilrod-Teller-Muto term. A common many-body dispersion expansion was extensively tested and an energy correction based on D4 polarizabilities is found to be advantageous for larger systems. Becke-Johnson-type damping parameters for DFT-D4 are determined for more than 60 common density functionals. For various standard energy benchmark sets DFT-D4 slightly but consistently outperforms DFT-D3. Especially for metal containing systems, the introduced charge dependence of the dispersion coefficients improves thermochemical properties. We suggest (DFT-)D4 as a physically improved and more sophisticated dispersion model in place of DFT-D3 for DFT calculations as well as other low-cost approaches like force-fields or semi-empirical models.</div>

A Generally Applicable Atomic-Charge Dependent London Dispersion Correction Scheme

2019 ◽  
Author(s):  
Eike Caldeweyher ◽  
Sebastian Ehlert ◽  
Andreas Hansen ◽  
Hagen Neugebauer ◽  
Sebastian Spicher ◽  
...  
Keyword(s):  
Density Functional ◽  
Dispersion Model ◽  
Low Cost ◽  
Atomic Charge ◽  
Body Part ◽  
Dispersion Interactions ◽  
Dispersion Coefficients ◽  
Charge Dependence ◽  
London Dispersion ◽  
Dynamic Polarizabilities

The D4 model is presented for the accurate computation of London dispersion interactions in density functional theory approximations (DFT-D4) and generally for atomistic modeling methods. In this successor to the DFT-D3 model, the atomic coordination-dependent dipole polarizabilities are scaled based on atomic partial charges which can be taken from various sources. For this purpose, a new charge-dependent parameter-economic scaling function is designed. Classical charges are obtained from an atomic electronegativity equilibration procedure for which efficient analytical derivatives are developed. A numerical Casimir-Polder integration of the atom-in-molecule dynamic polarizabilities yields charge- and geometry-dependent dipole-dipole dispersion coefficients. Similar to the D3 model, the dynamic polarizabilities are pre-computed by time-dependent DFT and elements up to radon are covered. For a benchmark set of 1225 dispersion coefficients, the D4 model achieves an unprecedented accuracy with a mean relative deviation of 3.8% compared to 4.7% for D3. In addition to the two-body part, three-body effects are described by an Axilrod-Teller-Muto term. A common many-body dispersion expansion was extensively tested and an energy correction based on D4 polarizabilities is found to be advantageous for some larger systems. Becke-Johnson-type damping parameters for DFT-D4 are determined for more than 60 common functionals. For various energy benchmark sets DFT-D4 slightly outperforms DFT-D3. Especially for metal containing systems, the introduced charge dependence improves thermochemical properties. We suggest (DFT-)D4 as a physically improved and more sophisticated dispersion model in place of DFT-D3 for DFT calculations as well as for other low-cost approaches like semi-empirical models.<br><br>

A Generally Applicable Atomic-Charge Dependent London Dispersion Correction Scheme

2019 ◽  
Author(s):  
Eike Caldeweyher ◽  
Sebastian Ehlert ◽  
Andreas Hansen ◽  
Hagen Neugebauer ◽  
Sebastian Spicher ◽  
...  
Keyword(s):  
Density Functional ◽  
Dispersion Model ◽  
Low Cost ◽  
Atomic Charge ◽  
Body Part ◽  
Dispersion Interactions ◽  
Dispersion Coefficients ◽  
Charge Dependence ◽  
London Dispersion ◽  
Dynamic Polarizabilities

The D4 model is presented for the accurate computation of London dispersion interactions in density functional theory approximations (DFT-D4) and generally for atomistic modeling methods. In this successor to the DFT-D3 model, the atomic coordination-dependent dipole polarizabilities are scaled based on atomic partial charges which can be taken from various sources. For this purpose, a new charge-dependent parameter-economic scaling function is designed. Classical charges are obtained from an atomic electronegativity equilibration procedure for which efficient analytical derivatives are developed. A numerical Casimir-Polder integration of the atom-in-molecule dynamic polarizabilities yields charge- and geometry-dependent dipole-dipole dispersion coefficients. Similar to the D3 model, the dynamic polarizabilities are pre-computed by time-dependent DFT and elements up to radon are covered. For a benchmark set of 1225 dispersion coefficients, the D4 model achieves an unprecedented accuracy with a mean relative deviation of 3.8% compared to 4.7% for D3. In addition to the two-body part, three-body effects are described by an Axilrod-Teller-Muto term. A common many-body dispersion expansion was extensively tested and an energy correction based on D4 polarizabilities is found to be advantageous for some larger systems. Becke-Johnson-type damping parameters for DFT-D4 are determined for more than 60 common functionals. For various energy benchmark sets DFT-D4 slightly outperforms DFT-D3. Especially for metal containing systems, the introduced charge dependence improves thermochemical properties. We suggest (DFT-)D4 as a physically improved and more sophisticated dispersion model in place of DFT-D3 for DFT calculations as well as for other low-cost approaches like semi-empirical models.<br><br>

scholarly journals On the Higher-Order Static Polarizabilities and Dispersion Coefficients of the Fullerenes: An Ab Initio Study

2020 ◽  
Author(s):  
Ka Un Lao ◽  
Yan Yang ◽  
Robert DiStasio
Keyword(s):  
Density Functional ◽  
Scaling Laws ◽  
Mechanical Response ◽  
Zero Point ◽  
Single Frequency ◽  
Dipole Polarizability ◽  
Dispersion Coefficients ◽  
Functional Theory ◽  
Molecular Dispersion ◽  
Insight Into

<div>In this work, we used finite-field derivative techniques and density functional theory (DFT) to compute the static isotropic polarizability series (<i>i.e.</i>, dipole, quadrupole, and octupole ) for the C<sub>60</sub>-C<sub>84</sub> fullerenes and quantitatively assess the intrinsic non-additivity in these fundamental response properties. Critical analysis of the derived effective scaling laws provides new insight into how the electronic structure of finite-sized fullerenes---a unique dichotomy of electron confinement and delocalization effects due to their quasi-spherical cage-like structures and encapsulated void spaces---simultaneously limits <i>and</i> enhances their quantum mechanical response to electric field perturbations. Corresponding molecular dispersion coefficients needed to describe the non-trivial van der Waals (vdW) interactions in fullerene-based systems were obtained by inputting the polarizabilities into the hollow sphere model within the modified single-frequency approximation. </div><div>Using first-order perturbation theory in conjunction with >140,000 DFT calculations, we also computed the non-negligible zero-point vibrational contributions (zpvc) to the dipole polarizability in C<sub>60</sub> and C<sub>70</sub>, thereby enabling direct comparison between theory and experiment for these quintessential nanostructures.</div>

Evaluating Force-Field London Dispersion Coefficients Using the Exchange-Hole Dipole Moment Model

2017 ◽  
Author(s):  
Mohamad Mohebifar ◽  
Erin R. Johnson ◽  
Christopher Rowley
Keyword(s):  
Dipole Moment ◽  
Density Functional ◽  
Force Fields ◽  
Mechanical Force ◽  
Pharmaceutical Chemistry ◽  
Dispersion Coefficients ◽  
Innovative Strategy ◽  
London Dispersion ◽  
Improved Accuracy ◽  
Mechanical Force Fields

<p>The exchange-hole dipole moment (XDM) model from density-functional theory predicts atomic and molecular London dispersion coefficients from first principles, providing an innovative strategy to validate the dispersion terms of molecular-mechanical force fields. In this work, the XDM model was used to obtain the London dispersion coefficients of 88 organic molecules relevant to biochemistry and pharmaceutical chemistry and the values compared with those derived from the Lennard-Jones parameters of the CGenFF, GAFF, OPLS, and Drude polarizable force fields…..(see full abstract). Finally, XDM-derived dispersion coefficients were used to parameterize molecular-mechanical force fields for five liquids – benzene, toluene, cyclohexane, n-pentane, and n-hexane – which resulted in improved accuracy in the computed enthalpies of vaporization despite only having to evaluate a much smaller section of the parameter space.</p>

scholarly journals On the Higher-Order Static Polarizabilities and Dispersion Coefficients of the Fullerenes: An Ab Initio Study

2020 ◽  
Author(s):  
Ka Un Lao ◽  
Yan Yang ◽  
Robert DiStasio
Keyword(s):  
Density Functional ◽  
Scaling Laws ◽  
Mechanical Response ◽  
Zero Point ◽  
Single Frequency ◽  
Dipole Polarizability ◽  
Dispersion Coefficients ◽  
Functional Theory ◽  
Molecular Dispersion ◽  
Insight Into

<div>In this work, we used finite-field derivative techniques and density functional theory (DFT) to compute the static isotropic polarizability series (<i>i.e.</i>, dipole, quadrupole, and octupole ) for the C<sub>60</sub>-C<sub>84</sub> fullerenes and quantitatively assess the intrinsic non-additivity in these fundamental response properties. Critical analysis of the derived effective scaling laws provides new insight into how the electronic structure of finite-sized fullerenes---a unique dichotomy of electron confinement and delocalization effects due to their quasi-spherical cage-like structures and encapsulated void spaces---simultaneously limits <i>and</i> enhances their quantum mechanical response to electric field perturbations. Corresponding molecular dispersion coefficients needed to describe the non-trivial van der Waals (vdW) interactions in fullerene-based systems were obtained by inputting the polarizabilities into the hollow sphere model within the modified single-frequency approximation. </div><div>Using first-order perturbation theory in conjunction with >140,000 DFT calculations, we also computed the non-negligible zero-point vibrational contributions (zpvc) to the dipole polarizability in C<sub>60</sub> and C<sub>70</sub>, thereby enabling direct comparison between theory and experiment for these quintessential nanostructures.</div>

scholarly journals Application of London Dispersion Corrected Density Functional Theory for Non-Covalent Ion-π Interactions

2020 ◽  
Author(s):  
Eike Caldeweyher ◽  
Sebastian Spicher ◽  
Andreas Hansen ◽  
Stefan Grimme
Keyword(s):  
Electrostatic Interactions ◽  
Density Functional ◽  
Dispersion Model ◽  
Computational Cost ◽  
Coupled Cluster ◽  
Dispersion Interactions ◽  
Field Methods ◽  
Approximate Methods ◽  
London Dispersion ◽  
Pi Interactions

<p>The strongly attractive non-covalent interactions of charged atoms or molecules with pi-systems are important bonding motifs in many chemical and biological systems. These so-called ion-pi interactions play a major role in enzymes, molecular recognition, and for the structure of proteins. To model ion-pi interactions with DFT, it is crucial</p><p>to include London dispersion interactions, whose importance for ion-pi interactions is often underestimated. In this work, several dispersion-corrected DFT methods are evaluated for inter- and intramolecular anionic- and anion-pi interactions in larger and practically relevant molecules. We compare the DFT results with MP2, while highly</p><p>accurate (local) coupled cluster values are provided as reference. The latter can also be a great help in the development and validation of approximate methods. We demonstrate that dispersion-uncorrected DFT underestimates ion-pi interactions significantly, even though electrostatic interactions dominate the overall binding. Accordingly, the</p><p>new charge dependent D4 dispersion model is found to be consistently better than the standard D3 correction. Dispersion-corrected DFT clearly outperforms MP2/CBS whereby the best performers come close to the accuracy limit of the reference values at considerably smaller computational cost. Due to its low cost, D4 can be combined</p><p>very well with semi-empirical QM and force field methods, which is important in the development of more accurate methods for modeling large (bio)chemical systems (e.g. proteins). Another important aspect in modeling these charged systems with DFT is the self-interaction error (SIE). However, we do not find it to constitute a significant problem. Overall, the double hybrid PWPB95-D4/QZ turned out to be the most reliable among all assessed methods in predicting ion-pi interactions, which opens up new perspectives for systems where coupled cluster calculations are no longer computationally feasible.</p>

Evaluating Force-Field London Dispersion Coefficients Using the Exchange-Hole Dipole Moment Model

2017 ◽  
Author(s):  
Mohamad Mohebifar ◽  
Erin R. Johnson ◽  
Christopher Rowley
Keyword(s):  
Dipole Moment ◽  
Density Functional ◽  
Force Fields ◽  
Mechanical Force ◽  
Pharmaceutical Chemistry ◽  
Dispersion Coefficients ◽  
Innovative Strategy ◽  
London Dispersion ◽  
Improved Accuracy ◽  
Mechanical Force Fields

<p>The exchange-hole dipole moment (XDM) model from density-functional theory predicts atomic and molecular London dispersion coefficients from first principles, providing an innovative strategy to validate the dispersion terms of molecular-mechanical force fields. In this work, the XDM model was used to obtain the London dispersion coefficients of 88 organic molecules relevant to biochemistry and pharmaceutical chemistry and the values compared with those derived from the Lennard-Jones parameters of the CGenFF, GAFF, OPLS, and Drude polarizable force fields…..(see full abstract). Finally, XDM-derived dispersion coefficients were used to parameterize molecular-mechanical force fields for five liquids – benzene, toluene, cyclohexane, n-pentane, and n-hexane – which resulted in improved accuracy in the computed enthalpies of vaporization despite only having to evaluate a much smaller section of the parameter space.</p>

scholarly journals Benchmarking London dispersion corrected density functional theory for noncovalent ion-pi interactions

2021 ◽  
Author(s):  
Sebastian Spicher ◽  
Eike Caldeweyher ◽  
Andreas Hansen ◽  
Stefan Grimme
Keyword(s):  
Electrostatic Interactions ◽  
Density Functional ◽  
Functional Performance ◽  
Dispersion Model ◽  
Coupled Cluster ◽  
Interaction Energies ◽  
Binding Motifs ◽  
Hybrid Functionals ◽  
London Dispersion ◽  
Pi Interactions

<p>The strongly attractive noncovalent interactions of charged atoms or molecules with p-systems are important binding motifs in many chemical and biological systems. These so-called ion-pi interactions play a major role in enzymes, molecular recognition, and for the structure of proteins. In this work, a molecular test set termed IONPI19 is compiled for inter- and intramolecular ion-pi interactions, which is well balanced between anionic and cationic systems. The IONPI19 set includes interaction energies of significantly larger molecules (up to 133 atoms) than in other ion-pi test sets and covers a broad range of binding motifs. Accurate (local) coupled cluster values are provided as reference. Overall, 18 density functional approximations, including seven (meta-)GGAs, seven hybrid functionals, and four double hybrid functionals combined with three different London dispersion corrections, are benchmarked for interaction energies. DFT results are further compared to wave function based methods such as MP2 and dispersion corrected Hartree-Fock. Also the performance</p><p>of semiempirical QM methods such as the GFNn-xTB and PMx family of methods is tested. It is shown that dispersion-uncorrected DFT underestimates ion-pi interactions significantly, even though electrostatic interactions dominate the overall binding. Accordingly, the new charge dependent D4 dispersion model is found to be consistently better than the standard D3 correction. Furthermore, the functional performance trend along Jacob’s ladder is generally obeyed and the reduction of the self-interaction error leads to an improvement of (double) hybrid functionals over (meta-)GGAs, even though the effect of the SIE is smaller than expected. Overall, the double hybrids PWPB95-D4/QZ and revDSD-PBEP86-D4/QZ turned out to be the most reliable among all assessed methods in predicting ion-pi interactions, which opens up new perspectives for systems where coupled cluster calculations are no longer computationally feasible.</p>

scholarly journals Application of London Dispersion Corrected Density Functional Theory for Non-Covalent Ion-π Interactions

2020 ◽  
Author(s):  
Eike Caldeweyher ◽  
Sebastian Spicher ◽  
Andreas Hansen ◽  
Stefan Grimme
Keyword(s):  
Electrostatic Interactions ◽  
Density Functional ◽  
Dispersion Model ◽  
Computational Cost ◽  
Coupled Cluster ◽  
Dispersion Interactions ◽  
Field Methods ◽  
Approximate Methods ◽  
London Dispersion ◽  
Pi Interactions

<p>The strongly attractive non-covalent interactions of charged atoms or molecules with pi-systems are important bonding motifs in many chemical and biological systems. These so-called ion-pi interactions play a major role in enzymes, molecular recognition, and for the structure of proteins. To model ion-pi interactions with DFT, it is crucial</p><p>to include London dispersion interactions, whose importance for ion-pi interactions is often underestimated. In this work, several dispersion-corrected DFT methods are evaluated for inter- and intramolecular anionic- and anion-pi interactions in larger and practically relevant molecules. We compare the DFT results with MP2, while highly</p><p>accurate (local) coupled cluster values are provided as reference. The latter can also be a great help in the development and validation of approximate methods. We demonstrate that dispersion-uncorrected DFT underestimates ion-pi interactions significantly, even though electrostatic interactions dominate the overall binding. Accordingly, the</p><p>new charge dependent D4 dispersion model is found to be consistently better than the standard D3 correction. Dispersion-corrected DFT clearly outperforms MP2/CBS whereby the best performers come close to the accuracy limit of the reference values at considerably smaller computational cost. Due to its low cost, D4 can be combined</p><p>very well with semi-empirical QM and force field methods, which is important in the development of more accurate methods for modeling large (bio)chemical systems (e.g. proteins). Another important aspect in modeling these charged systems with DFT is the self-interaction error (SIE). However, we do not find it to constitute a significant problem. Overall, the double hybrid PWPB95-D4/QZ turned out to be the most reliable among all assessed methods in predicting ion-pi interactions, which opens up new perspectives for systems where coupled cluster calculations are no longer computationally feasible.</p>

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