scholarly journals Extension and Evaluation of the D4 London Dispersion Model for Periodic Systems

2019 ◽  
Author(s):  
Eike Caldeweyher ◽  
Jan-Michael Mewes ◽  
Sebastian Ehlert ◽  
Stefan Grimme
Keyword(s):  
Materials Science ◽  
Dispersion Model ◽  
Low Cost ◽  
Chem Phys ◽  
Periodic Systems ◽  
Computationally Efficient ◽  
Dispersion Energy ◽  
Alkaline Metals ◽  
Standard Application ◽  
London Dispersion

<div>London-dispersion effects are of great relevance to many aspects of materials science and for various condensed matter problems. In this work we present an adaptation and implementation of the DFT-D4 model [Caldeweyher et al., J. Chem. Phys., 2019, 150, 154122] for periodic systems. The main new ingredient are better computed reference polarizabilities for high coordination numbers (including alkaline metals, earth alkaline metals, and d-metals of group 3-5), which are consistently derived from periodic electrostatically embedded cluster calculations. Some technical extensions have been added concerning the coordination number, the partial charges, and the dispersion energy expression. To demonstrate the performance of the improved scheme, several test cases are considered, for which we compare D4 results to those of its predecessor D3(BJ) as well as to several other dispersion corrected methods. The largest improvements are observed for solid state polarizabilities of 16 inorganic salts, where the new D4 model achieves an unprecedented accuracy, surpassing its predecessor as well as other, computationally much more demanding approaches. For cell volumes and lattice energies of two sets of chemically diverse molecular crystals, the accuracy gain is less pronounced compared to the already excellently performing D3(BJ) method. For the challenging adsorption energies of small organic molecules on metallic as well as on ionic surfaces, DFT-D4 provides high accuracy similar to MBD/HI or uncorrected DFT/SCAN approaches. These results suggest the standard application of the proposed periodic D4 model as a physically improved yet computationally efficient dispersion correction for standard DFT calculations as well as low-cost approaches like semi-empirical or even force-field models.</div>

scholarly journals Extension and Evaluation of the D4 London Dispersion Model for Periodic Systems

2019 ◽  
Author(s):  
Eike Caldeweyher ◽  
Jan-Michael Mewes ◽  
Sebastian Ehlert ◽  
Stefan Grimme
Keyword(s):  
Materials Science ◽  
Dispersion Model ◽  
Low Cost ◽  
Chem Phys ◽  
Periodic Systems ◽  
Computationally Efficient ◽  
Dispersion Energy ◽  
Alkaline Metals ◽  
Standard Application ◽  
London Dispersion

<div>London-dispersion effects are of great relevance to many aspects of materials science and for various condensed matter problems. In this work we present an adaptation and implementation of the DFT-D4 model [Caldeweyher et al., J. Chem. Phys., 2019, 150, 154122] for periodic systems. The main new ingredient are better computed reference polarizabilities for high coordination numbers (including alkaline metals, earth alkaline metals, and d-metals of group 3-5), which are consistently derived from periodic electrostatically embedded cluster calculations. Some technical extensions have been added concerning the coordination number, the partial charges, and the dispersion energy expression. To demonstrate the performance of the improved scheme, several test cases are considered, for which we compare D4 results to those of its predecessor D3(BJ) as well as to several other dispersion corrected methods. The largest improvements are observed for solid state polarizabilities of 16 inorganic salts, where the new D4 model achieves an unprecedented accuracy, surpassing its predecessor as well as other, computationally much more demanding approaches. For cell volumes and lattice energies of two sets of chemically diverse molecular crystals, the accuracy gain is less pronounced compared to the already excellently performing D3(BJ) method. For the challenging adsorption energies of small organic molecules on metallic as well as on ionic surfaces, DFT-D4 provides high accuracy similar to MBD/HI or uncorrected DFT/SCAN approaches. These results suggest the standard application of the proposed periodic D4 model as a physically improved yet computationally efficient dispersion correction for standard DFT calculations as well as low-cost approaches like semi-empirical or even force-field models.</div>

Extension and evaluation of the D4 London-dispersion model for periodic systems

2020 ◽  
Vol 22 (16) ◽  
pp. 8499-8512 ◽  
Author(s):  
Eike Caldeweyher ◽  
Jan-Michael Mewes ◽  
Sebastian Ehlert ◽  
Stefan Grimme
Keyword(s):  
Dispersion Model ◽  
Chem Phys ◽  
Periodic Systems ◽  
London Dispersion

We present an extension of the DFT-D4 model [J. Chem. Phys., 2019, 150, 154122] for periodic systems.

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 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>

scholarly journals Understanding Spatial Variability of NO2 in Urban Areas Using Spatial Modelling and Data Fusion Approaches

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 179
Author(s):  
Said Munir ◽  
Martin Mayfield ◽  
Daniel Coca
Keyword(s):  
Data Fusion ◽  
Spatial Variability ◽  
Urban Areas ◽  
Road Traffic ◽  
Dispersion Model ◽  
Low Cost ◽  
Spatial Modelling ◽  
City Centre ◽  
Small Scale ◽  
The City

Small-scale spatial variability in NO2 concentrations is analysed with the help of pollution maps. Maps of NO2 estimated by the Airviro dispersion model and land use regression (LUR) model are fused with measured NO2 concentrations from low-cost sensors (LCS), reference sensors and diffusion tubes. In this study, geostatistical universal kriging was employed for fusing (integrating) model estimations with measured NO2 concentrations. The results showed that the data fusion approach was capable of estimating realistic NO2 concentration maps that inherited spatial patterns of the pollutant from the model estimations and adjusted the modelled values using the measured concentrations. Maps produced by the fusion of NO2-LCS with NO2-LUR produced better results, with r-value 0.96 and RMSE 9.09. Data fusion adds value to both measured and estimated concentrations: the measured data are improved by predicting spatiotemporal gaps, whereas the modelled data are improved by constraining them with observed data. Hotspots of NO2 were shown in the city centre, eastern parts of the city towards the motorway (M1) and on some major roads. Air quality standards were exceeded at several locations in Sheffield, where annual mean NO2 levels were higher than 40 µg/m3. Road traffic was considered to be the dominant emission source of NO2 in Sheffield.

scholarly journals Low-Cost Molecular Excited States from a State-Averaged Resonating Hartree-Fock Approach

2019 ◽  
Author(s):  
Jacob Nite ◽  
Carlos A. Jimenez-Hoyos
Keyword(s):  
Excited States ◽  
Configuration Interaction ◽  
Low Cost ◽  
Computational Cost ◽  
Mean Field ◽  
Chem Phys ◽  
Spin Projection ◽  
Excitation Energies ◽  
Hartree Fock ◽  
Orbital Relaxation

Quantum chemistry methods that describe excited states on the same footing as the ground state are generally scarce. In previous work, Gill et al. (J. Phys. Chem. A 112, 13164 (2008)) and later Sundstrom and Head-Gordon (J. Chem. Phys. 140, 114103 (2014)) considered excited states resulting from a non-orthogonal configuration interaction (NOCI) on stationary solutions of the Hartree–Fock equations. We build upon those contributions and present the state-averaged resonating Hartree–Fock (sa-ResHF) method, which differs from NOCI in that spin-projection and orbital relaxation effects are incorporated from the onset. Our results in a set of small molecules (alanine, formaldehyde, acetaldehyde, acetone, formamide, and ethylene) suggest that sa-ResHF excitation energies are a notable improvement over configuration interaction singles (CIS), at a mean-field computational cost. The orbital relaxation in sa-ResHF, in the presence of a spin-projection operator, generally results in excitation energies that are closer to the experimental values than the corresponding NOCI ones.

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