A quantitative evaluation of computational methods to accelerate the study of alloxazine-derived electroactive compounds for energy storage

AbstractHigh-throughput computational screening (HTCS) is a powerful approach for the rational and time-efficient design of electroactive compounds. The effectiveness of HTCS is dependent on accuracy and speed at which the performance descriptors can be estimated for possibly millions of candidate compounds. Here, a systematic evaluation of computational methods, including force field (FF), semi-empirical quantum mechanics (SEQM), density functional based tight binding (DFTB), and density functional theory (DFT), is performed on the basis of their accuracy in predicting the redox potentials of redox-active organic compounds. Geometry optimizations at low-level theories followed by single point energy (SPE) DFT calculations that include an implicit solvation model are found to offer equipollent accuracy as the high-level DFT methods, albeit at significantly lower computational costs. Effects of implicit solvation on molecular geometries and SPEs, and their overall effects on the prediction accuracy of redox potentials are analyzed in view of computational cost versus prediction accuracy, which outlines the best choice of methods corresponding to a desired level of accuracy. The modular computational approach is applicable for accelerating the virtual studies on functional quinones and the respective discovery of candidate compounds for energy storage.

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A Quantitative Evaluation of Computational Methods to Accelerate the Study of Alloxazine-Derived Electroactive Compounds for Energy Storage

10.26434/chemrxiv.12931226 ◽

2020 ◽

Author(s):

Qi Zhang ◽

Abhishek Khetan ◽

Süleyman Er

Keyword(s):

Energy Storage ◽

Computational Methods ◽

High Throughput ◽

Density Functional ◽

Computational Cost ◽

Orbital Energy ◽

Redox Potentials ◽

Redox Flow Batteries ◽

Computational Screening ◽

Flow Batteries

Alloxazines are a promising class of organic electroactive molecules for application in aqueous redox flow batteries. Preliminary studies show that structural modifications of alloxazines with electron-donating and/or -withdrawing functional groups help in tuning of their redox properties. High-throughput computational screening enables rational and time-efficient discovery of functional compounds. The effectiveness of high-throughput computational screening efforts is strongly dependent on the accuracy and speed at which the performance descriptors are estimated for a large pool of candidate compounds. Here, we performed a quantitative study to assess the performance of computational methods, including the forcefield based molecular mechanics, semi-empirical quantum mechanics, density functional based tight binding, and density functional theory, on the basis of their accuracy and computational cost in predicting the redox potentials of electroactive alloxazines. We compared the performances of various energy-based descriptors, including the redox reaction energy and the frontier orbital energies of the reactant and product molecules. We found that the lowest unoccupied molecular orbital energy of the reactant molecules is the best performing descriptor for the alloxazines, which is in contrast to other classes of molecules, such as quinones that we reported earlier. Importantly, we present a flexible in silico approach to accelerate both the singly and the high-throughput computational screening studies, therewithal considering the level of accuracy vs measured electrochemical data, that is principally applicable for the discovery of efficient, alloxazine-derived organic compounds for energy storage in aqueous redox flow batteries.

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Comparison of Computational Chemistry Methods for the Discovery of Quinone-Based Electroactive Compounds for Energy Storage

10.26434/chemrxiv.12893825 ◽

2020 ◽

Author(s):

Qi Zhang ◽

Abhishek Khetan ◽

Süleyman Er

Keyword(s):

Energy Storage ◽

Prediction Accuracy ◽

Density Functional ◽

Single Point ◽

Computational Cost ◽

Systematic Evaluation ◽

Redox Potentials ◽

Implicit Solvation ◽

Point Energy ◽

Computational Screening

High-throughput computational screening (HTCS) is an approach that can enable rational and time-efficient discovery of electroactive compounds. The effectiveness of HTCS is dependent on the accuracy and speed at which the performance descriptors can be estimated for possibly millions of candidate compounds. Here, a systematic evaluation of computational methods, including force field (FF), semi-empirical quantum mechanics (SEQM), density functional based tight binding (DFTB), and density functional theory (DFT), is performed on the basis of their accuracy in predicting the redox potentials of redox-active organic compounds. Geometry optimizations at lower level theories followed by single point energy (SPE) DFT calculations including an implicit solvation model are found to offer equipollent accuracy as the higher level DFT methods, albeit at significantly lower computational costs. Effects of implicit solvation on molecular geometries and SPEs, and their overall effects on the prediction accuracy of redox potentials are analyzed in view of computational cost versus prediction accuracy, which outlines the best choice of methods corresponding to a desired level of accuracy. The modular computational approach presented here is expected to be applicable for accelerating virtual studies on functional quinones and the respective discovery of candidate compounds for energy storage.

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Comparison of Computational Chemistry Methods for the Discovery of Quinone-Based Electroactive Compounds for Energy Storage

10.26434/chemrxiv.12893825.v1 ◽

2020 ◽

Author(s):

Qi Zhang ◽

Abhishek Khetan ◽

Süleyman Er

Keyword(s):

Energy Storage ◽

Prediction Accuracy ◽

Density Functional ◽

Single Point ◽

Computational Cost ◽

Systematic Evaluation ◽

Redox Potentials ◽

Implicit Solvation ◽

Point Energy ◽

Computational Screening

High-throughput computational screening (HTCS) is an approach that can enable rational and time-efficient discovery of electroactive compounds. The effectiveness of HTCS is dependent on the accuracy and speed at which the performance descriptors can be estimated for possibly millions of candidate compounds. Here, a systematic evaluation of computational methods, including force field (FF), semi-empirical quantum mechanics (SEQM), density functional based tight binding (DFTB), and density functional theory (DFT), is performed on the basis of their accuracy in predicting the redox potentials of redox-active organic compounds. Geometry optimizations at lower level theories followed by single point energy (SPE) DFT calculations including an implicit solvation model are found to offer equipollent accuracy as the higher level DFT methods, albeit at significantly lower computational costs. Effects of implicit solvation on molecular geometries and SPEs, and their overall effects on the prediction accuracy of redox potentials are analyzed in view of computational cost versus prediction accuracy, which outlines the best choice of methods corresponding to a desired level of accuracy. The modular computational approach presented here is expected to be applicable for accelerating virtual studies on functional quinones and the respective discovery of candidate compounds for energy storage.

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A Quantitative Evaluation of Computational Methods to Accelerate the Study of Alloxazine-Derived Electroactive Compounds for Energy Storage

10.26434/chemrxiv.12931226.v1 ◽

2020 ◽

Author(s):

Qi Zhang ◽

Abhishek Khetan ◽

Süleyman Er

Keyword(s):

Energy Storage ◽

Computational Methods ◽

High Throughput ◽

Density Functional ◽

Computational Cost ◽

Orbital Energy ◽

Redox Potentials ◽

Redox Flow Batteries ◽

Computational Screening ◽

Flow Batteries

Alloxazines are a promising class of organic electroactive molecules for application in aqueous redox flow batteries. Preliminary studies show that structural modifications of alloxazines with electron-donating and/or -withdrawing functional groups help in tuning of their redox properties. High-throughput computational screening enables rational and time-efficient discovery of functional compounds. The effectiveness of high-throughput computational screening efforts is strongly dependent on the accuracy and speed at which the performance descriptors are estimated for a large pool of candidate compounds. Here, we performed a quantitative study to assess the performance of computational methods, including the forcefield based molecular mechanics, semi-empirical quantum mechanics, density functional based tight binding, and density functional theory, on the basis of their accuracy and computational cost in predicting the redox potentials of electroactive alloxazines. We compared the performances of various energy-based descriptors, including the redox reaction energy and the frontier orbital energies of the reactant and product molecules. We found that the lowest unoccupied molecular orbital energy of the reactant molecules is the best performing descriptor for the alloxazines, which is in contrast to other classes of molecules, such as quinones that we reported earlier. Importantly, we present a flexible in silico approach to accelerate both the singly and the high-throughput computational screening studies, therewithal considering the level of accuracy vs measured electrochemical data, that is principally applicable for the discovery of efficient, alloxazine-derived organic compounds for energy storage in aqueous redox flow batteries.

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Thermal Properties of Divalent Metal Oxides: CaO as a Prototype

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.209.190 ◽

2013 ◽

Vol 209 ◽

pp. 190-193

Author(s):

Nisarg K. Bhatt ◽

Brijmohan Y. Thakore ◽

P.R. Vyas ◽

A.Y. Vahora ◽

Asvin R. Jani

Keyword(s):

Density Functional ◽

Tight Binding ◽

Mean Field ◽

Field Potential ◽

Theoretical Data ◽

Test Case ◽

Generalized Gradient ◽

Core Electrons ◽

Vibrational Free Energy ◽

Semi Empirical

Commonly employed quasiharmonic approximation (QHA) is inadequate to account for intrinsic anharmonism such as phonon-phonon interaction, vacancy contribution, etc. Though anharmonic contributions are important at high temperatures and low pressure, complete ab initio calculations are scanty due largely to laborious computational requirements. Nevertheless, some simple semi-empirical schemes can be used effectively to incorporate the anharmonism. In this regards, in the present study we have proposed a simple computational scheme to include the effect of vacancy directly into the description within the mean-field potential approach, which calculates vibrational free energy of ions. Validity of the scheme is verified by taking calcium oxide as a test case. Equilibrium properties at (T,P) = (0,0) condition is obtained within the tight-binding second-moment approximation (TB-SMA), whose parameters were determined through first principles density functional theory. Kohn-Sham equations for core electrons were solved using ultrasoft plane-wave pseudopotential employing the generalized gradient approximation for exchange and correlation. Present findings for thermal expansion and high-T EOS clearly show perceptible improvement over the case when vacancy contribution was not included. Some related thermodynamic properties are also calculated and compared with the available experimental and theoretical data.

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Density functional tight binding: values of semi-empirical methods in an ab initio era

Physical Chemistry Chemical Physics ◽

10.1039/c4cp00908h ◽

2014 ◽

Vol 16 (28) ◽

pp. 14368-14377 ◽

Cited By ~ 75

Author(s):

Qiang Cui ◽

Marcus Elstner

Keyword(s):

Density Functional Theory ◽

Ab Initio ◽

Density Functional ◽

Tight Binding ◽

Empirical Methods ◽

Functional Theory ◽

Hartree Fock ◽

Semi Empirical

Semi-empirical (SE) methods are derived from Hartree–Fock (HF) or Density Functional Theory (DFT) by neglect and approximation of electronic integrals.

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SoftBV – a software tool for screening the materials genome of inorganic fast ion conductors

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520618015718 ◽

2019 ◽

Vol 75 (1) ◽

pp. 18-33 ◽

Cited By ~ 35

Author(s):

Haomin Chen ◽

Lee Loong Wong ◽

Stefan Adams

Keyword(s):

Force Field ◽

High Throughput ◽

High Throughput Screening ◽

Density Functional ◽

Inorganic Compounds ◽

Computational Cost ◽

Lewis Base ◽

Computational Screening ◽

Wide Range ◽

Dft Simulations

The identification of materials for advanced energy-storage systems is still mostly based on experimental trial and error. Increasingly, computational tools are sought to accelerate materials discovery by computational predictions. Here are introduced a set of computationally inexpensive software tools that exploit the bond-valence-based empirical force field previously developed by the authors to enable high-throughput computational screening of experimental or simulated crystal-structure models of battery materials predicting a variety of properties of technological relevance, including a structure plausibility check, surface energies, an inventory of equilibrium and interstitial sites, the topology of ion-migration paths in between those sites, the respective migration barriers and the site-specific attempt frequencies. All of these can be predicted from CIF files of structure models at a minute fraction of the computational cost of density functional theory (DFT) simulations, and with the added advantage that all the relevant pathway segments are analysed instead of arbitrarily predetermined paths. The capabilities and limitations of the approach are evaluated for a wide range of ion-conducting solids. An integrated simple kinetic Monte Carlo simulation provides rough (but less reliable) predictions of the absolute conductivity at a given temperature. The automated adaptation of the force field to the composition and charge distribution in the simulated material allows for a high transferability of the force field within a wide range of Lewis acid–Lewis base-type ionic inorganic compounds as necessary for high-throughput screening. While the transferability and precision will not reach the same levels as in DFT simulations, the fact that the computational cost is several orders of magnitude lower allows the application of the approach not only to pre-screen databases of simple structure prototypes but also to structure models of complex disordered or amorphous phases, and provides a path to expand the analysis to charge transfer across interfaces that would be difficult to cover by ab initio methods.

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Combined tight-binding/DFT investigation of the electronic structure of triimine-platinum(II)/TCNQ extended stacks,

Canadian Journal of Chemistry ◽

10.1139/v08-175 ◽

2009 ◽

Vol 87 (7) ◽

pp. 775-783 ◽

Cited By ~ 5

Author(s):

Hassan Rabaâ ◽

Thomas R. Cundari ◽

Mohammad A. Omary

Keyword(s):

Electronic Structure ◽

Density Functional ◽

Tight Binding ◽

Negative Energy ◽

Large Contribution ◽

Redox Potentials ◽

Absorption Bands ◽

Metallic Behavior ◽

Charge Delocalization ◽

Donor Acceptor

. The [Pt(tbtrpy)(X)][TCNQ] (X = OH or SH) complexes form sandwich stacks with nitrile acceptors leading to extended-chain supramolecular assemblies, tbtrpy = 4,4′,4″-tert-Bu3-2,2′:6′,2″-terpyridine. Calculations with the extended Hückel tight-binding (EHTB) method are performed upon crystalline {[Pt (tbtrpy)(X)][TCNQ]}∞ species to analyze their electronic structure and consequent properties, TCNQ = 7,7,8,8-tetracyanoquinodimethane. The donor/acceptor extended chains in the solid state are predicted to exhibit metallic behavior with a large contribution from π and π* bands of TCNQ to the valence and conduction bands, respectively. Moreover, the valence band moves upward (i.e., to a less negative energy) for X = SH as compared to X = OH. Density functional theory (DFT) calculations suggest that this is due to large thiolate character in the HOMO of the square-planar donor complex, which also supports the experimental assignment of the electronic absorption bands and redox potentials. Calculations of infrared (νCN bands of TCNQ) and structural (CC bond lengths within TCNQ) data explain the metallic behavior of the stacks in terms of charge delocalization, leading to fractionally-charged species of the form [Pt(tbtrpy)X](1+δ)+[TCNQ](1+δ)- with δ > 0 and a greater δ value for X = SH vs OH.

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A High-Throughput Screening Approach for the Optoelectronic Properties of Conjugated Polymers

10.26434/chemrxiv.6181841.v2 ◽

2018 ◽

Author(s):

Liam Wilbraham ◽

Enrico Berardo ◽

Lukas Turcani ◽

Kim Jelfs ◽

Martijn Zwijnenburg

Keyword(s):

Conjugated Polymers ◽

Electronic Properties ◽

High Throughput ◽

High Throughput Screening ◽

Density Functional ◽

Tight Binding ◽

Computational Cost ◽

Quality Data ◽

Minor Variation ◽

Screening Approach

We propose a general high-throughput virtual screening approach for the optical and electronic properties of conjugated polymers. This approach makes use of the recently developed xTB family of low-computational-cost density functional tight-binding methods from Grimme and co-workers, calibrated here to (TD-)DFT data computed for a representative diverse set of (co-)polymers. Parameters drawn from the resulting calibration using a linear model can then be applied to the xTB derived results for new polymers, thus generating near DFT-quality data with orders of magnitude reduction in computational cost. As a result, after an initial computational investment for calibration, this approach can be used to quickly and accurately screen on the order of thousands of polymers for target applications. We also demonstrate that the (opto)electronic properties of the conjugated polymers show only a very minor variation when considering different conformers and that the results of high-throughput screening are therefore expected to be relatively insensitive with respect to the conformer search methodology applied.

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