Density-functional expansion methods: grand challenges

Giese, Timothy J.; York, Darrin M.

doi:10.1007/978-3-642-34450-3_5

Cited by 4 publications

(6 citation statements)

References 41 publications

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“…While the limitation to second order effects at first may seem overly restrictive, recent work e.g. by Giese and York, 41,42 has shown that carefully conducted second order expansions can yield polarization responses and even geometries nearly indistinguishable from the full KS DFT case. In section 2 we show ACKS2 to go even one step further, yielding excellent agreement not only for the induced molecular dipole moments but also the polarization energy.…”

Section: Theoretical Background Of the Acks2 Methodsmentioning

confidence: 99%

“…Similar failures can be found for straightforward applications of density functional tight binding DFTB2. 42 Both of these can be substantially improved though, by coupling the respective ground state electronic structures to carefully parametrized implementations of the chemical potential equalization (CPE). A single post-processing step of CPE, for example, yields an RME of 12% and 3% for induced dipole moments and molecular polarizabilties, respectively for MNDO, 47 and 5% for molecular polarizabilities in DFTB2.…”

Section: Comparison To Other Polarizeable Methodsmentioning

confidence: 99%

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Toward First-Principles-Level Polarization Energies in Force Fields: A Gaussian Basis for the Atom-Condensed Kohn–Sham Method

Gütlein

Lang

Reuter

et al. 2019

J. Chem. Theory Comput.

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The last twenty years of force field development have shown that even well parametrized classical models need to at least approximate the dielectric response of molecular systems-based e.g. on atomic polarizabilities-in order to correctly render their structural and dynamic properties. Yet, despite great advances most approaches tend to be based on ad hoc assumptions and often insufficiently capture the dielectric response of the system to external perturbations, such as e.g. charge carriers in semiconducting materials. A possible remedy was recently introduced with the atom-condensed Kohn-Sham density-functional theory approximated to second order (ACKS2), which is fully 1 derived from first principles. Unfortunately, specifically its reliance on first-principles derived parameters so far precluded the widespread adoption of ACKS2. Opening up ACKS2 for general use, we here present a reformulation of the method in terms of Gaussian basis functions, which allows us to determine many of the ACKS2 parameters analytically. Two sets of parameters depending on exchange-correlation interactions are still calculated numerically, but we show that they could be straightforwardly parametrized owing to the smoothness of the new basis. Our approach exhibits three crucial benefits for future applications in force fields, i) efficiency, ii) accuracy, and iii) transferability. We numerically validate our Gaussian augmented ACKS2 model for a set of small hydrocarbons which shows a very good agreement with densityfunctional theory reference calculations. To further demonstrate the method's accuracy and transferability for realistic systems, we calculate polarization responses and energies of anthracene and tetracene, two major building blocks in organic semiconductors.

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Section: Theoretical Background Of the Acks2 Methodsmentioning

confidence: 99%

Section: Comparison To Other Polarizeable Methodsmentioning

confidence: 99%

Toward First-Principles-Level Polarization Energies in Force Fields: A Gaussian Basis for the Atom-Condensed Kohn–Sham Method

Gütlein

Lang

Reuter

et al. 2019

J. Chem. Theory Comput.

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“… 26 , 27 Therefore, despite the tremendous progress in ab initio QM and QM/MM methods, it remains meaningful to explore further development of the semiempirical type of QM methods. 28 − 31 …”

Section: Introductionmentioning

confidence: 99%

Parameterization of DFTB3/3OB for Sulfur and Phosphorus for Chemical and Biological Applications

Gaus

Elstner

et al. 2014

J. Chem. Theory Comput.

322

337

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We report the parametrization of the approximate density functional tight binding method, DFTB3, for sulfur and phosphorus. The parametrization is done in a framework consistent with our previous 3OB set established for O, N, C, and H, thus the resulting parameters can be used to describe a broad set of organic and biologically relevant molecules. The 3d orbitals are included in the parametrization, and the electronic parameters are chosen to minimize errors in the atomization energies. The parameters are tested using a fairly diverse set of molecules of biological relevance, focusing on the geometries, reaction energies, proton affinities, and hydrogen bonding interactions of these molecules; vibrational frequencies are also examined, although less systematically. The results of DFTB3/3OB are compared to those from DFT (B3LYP and PBE), ab initio (MP2, G3B3), and several popular semiempirical methods (PM6 and PDDG), as well as predictions of DFTB3 with the older parametrization (the MIO set). In general, DFTB3/3OB is a major improvement over the previous parametrization (DFTB3/MIO), and for the majority cases tested here, it also outperforms PM6 and PDDG, especially for structural properties, vibrational frequencies, hydrogen bonding interactions, and proton affinities. For reaction energies, DFTB3/3OB exhibits major improvement over DFTB3/MIO, due mainly to significant reduction of errors in atomization energies; compared to PM6 and PDDG, DFTB3/3OB also generally performs better, although the magnitude of improvement is more modest. Compared to high-level calculations, DFTB3/3OB is most successful at predicting geometries; larger errors are found in the energies, although the results can be greatly improved by computing single point energies at a high level with DFTB3 geometries. There are several remaining issues with the DFTB3/3OB approach, most notably its difficulty in describing phosphate hydrolysis reactions involving a change in the coordination number of the phosphorus, for which a specific parametrization (3OB/OPhyd) is developed as a temporary solution; this suggests that the current DFTB3 methodology has limited transferability for complex phosphorus chemistry at the level of accuracy required for detailed mechanistic investigations. Therefore, fundamental improvements in the DFTB3 methodology are needed for a reliable method that describes phosphorus chemistry without ad hoc parameters. Nevertheless, DFTB3/3OB is expected to be a competitive QM method in QM/MM calculations for studying phosphorus/sulfur chemistry in condensed phase systems, especially as a low-level method that drives the sampling in a dual-level QM/MM framework.

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“…In addition, the description of electrostatic fluctuations in weakly bound systems may be poorly described via the Mulliken charges. Improvement of electric dipole polarizabilities and polarization energies in the framework of DFTB2 [68] and DFTB3 [53,69] was proposed within the so-called Chemical Potential Equalization (CPE) scheme. The principle is based on an expansion of the energy as a response to the field in the vicinity of the field-less DFTB density…”

Section: Non-covalent Interactionsmentioning

confidence: 99%

Density-functional tight-binding: basic concepts and applications to molecules and clusters

Spiegelman

Tarrat

Cuny

et al. 2020

Advances in Physics: X

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The scope of this article is to present an overview of the Density Functional based Tight Binding (DFTB) method and its applications. The paper introduces the basics of DFTB and its standard formulation up to second order. It also addresses methodological developments such as third order expansion, inclusion of non-covalent interactions, schemes to solve the self-interaction error, implementation of long-range short-range separation, treatment of excited states via the time-dependent DFTB scheme, inclusion of DFTB in hybrid high-level/low level schemes (DFT/DFTB or DFTB/MM), fragment decomposition of large systems, large scale potential energy landscape exploration with molecular dynamics in ground or excited states, nonadiabatic dynamics. A number of applications are reviewed, focusing on -(i)-the variety of systems that have been studied such as small molecules, large molecules and biomolecules, bare or functionalized clusters, supported or embedded systems, and -(ii)-properties and processes, such as vibrational spectroscopy, collisions, fragmentation, thermodynamics or non-adiabatic dynamics. Finally outlines and perspectives are given. ARTICLE HISTORY

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Density-functional expansion methods: grand challenges

Cited by 4 publications

References 41 publications

Toward First-Principles-Level Polarization Energies in Force Fields: A Gaussian Basis for the Atom-Condensed Kohn–Sham Method

Toward First-Principles-Level Polarization Energies in Force Fields: A Gaussian Basis for the Atom-Condensed Kohn–Sham Method

Parameterization of DFTB3/3OB for Sulfur and Phosphorus for Chemical and Biological Applications

Density-functional tight-binding: basic concepts and applications to molecules and clusters

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