Universal tight binding model for chemical reactions in solution and at surfaces. III. Stoichiometric and reduced surfaces of titania and the adsorption of water

Lozovoi, A.Y.; Pashov, Dimitar; Sheppard, Terence; Kohanoff, Jorge; Paxton, Anthony

doi:10.1063/1.4890492

Cited by 5 publications

(12 citation statements)

References 73 publications

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“…The two terms in (2) are the basic tenets of the standard TB approach pioneered by Slater and Koster 25 and built into a working scheme for much of the periodic 27 However, the theory is equally applicable if the density matrix is obtained in real space. 28, 29 E pair is a sum of usually repulsive pair potentials.…”

Section: Self Consistent Polarizable Ion Tight Binding (Pitb)mentioning

confidence: 99%

“…This is a case where a compromise needs to be made. Another point of note is that V ppσ controls the distance dependence of the attractive band energy, E (2) band . A larger value of V ppσ results in a stronger band energy at distances sampled during normal molecular vibration.…”

Section: On-site Parametersmentioning

confidence: 99%

“…20,34 The second aspect is particularly important as it is this feature that allows us to study polarizability of the ionic charge, which has led to an understanding, among other things, of the stabilization of tetragonal and monoclinic phases in zirconia 35 and the dielectric constant of water. 1,3 In PITB theory we seek a self consistent field approximation to E (2) . To this end we write an energy functional to replace (2)…”

Section: Self Consistent Polarizable Ion Tight Binding (Pitb)mentioning

confidence: 99%

“…1). To ensure all functions decay exactly to zero smoothly we multiply the functions (4) and (5) by 5th order polynomials defined between certain bond distances r (1) cut and r (2) cut . The polynomials have value, first derivative and second derivative matching those of the function to be cut off at r (1) cut and value, first derivative and second derivative equal to zero at r (2) cut .…”

Section: Parametersmentioning

confidence: 99%

“…In Paper II 1 we describe models for the solvent and in Paper III we describe adsorption and dissociation of water at the surfaces of transition metal oxides. 2 Our approach is unique compared with existing classical and semi-empirical quantum mechanical models in that each particular element (C, O, H, and the transition metals) is described by a parameter set which is independent of the environment. So, for example, an oxygen atom may transfer seamlessly between an oxide phase and a water or alcohol molecule.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Universal tight binding model for chemical reactions in solution and at surfaces. I. Organic molecules

Sheppard

Lozovoi

Pashov

et al. 2014

The Journal of Chemical Physics

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Articles you may be interested inAs is now well established, a first order expansion of the Hohenberg-Kohn total energy density functional about a trial input density, namely, the Harris-Foulkes functional, can be used to rationalize a non self consistent tight binding model. If the expansion is taken to second order then the energy and electron density matrix need to be calculated self consistently and from this functional one can derive a charge self consistent tight binding theory. In this paper we have used this to describe a polarizable ion tight binding model which has the benefit of treating charge transfer in point multipoles. This admits a ready description of ionic polarizability and crystal field splitting. It is necessary in constructing such a model to find a number of parameters that mimic their more exact counterparts in the density functional theory. We describe in detail how this is done using a combination of intuition, exact analytical fitting, and a genetic optimization algorithm. Having obtained model parameters we show that this constitutes a transferable scheme that can be applied rather universally to small and medium sized organic molecules. We have shown that the model gives a good account of static structural and dynamic vibrational properties of a library of molecules, and finally we demonstrate the model's capability by showing a real time simulation of an enolization reaction in aqueous solution.In two subsequent papers, we show that the model is a great deal more general in that it will describe solvents and solid substrates and that therefore we have created a self consistent quantum mechanical scheme that may be applied to simulations in heterogeneous catalysis. © 2014 AIP Publishing LLC.

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Section: Self Consistent Polarizable Ion Tight Binding (Pitb)mentioning

confidence: 99%

Section: On-site Parametersmentioning

confidence: 99%

Section: Self Consistent Polarizable Ion Tight Binding (Pitb)mentioning

confidence: 99%

Section: Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Universal tight binding model for chemical reactions in solution and at surfaces. I. Organic molecules

Sheppard

Lozovoi

Pashov

et al. 2014

The Journal of Chemical Physics

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Learning to Use the Force: Fitting Repulsive Potentials in Density-Functional Tight-Binding with Gaussian Process Regression

Panosetti

Engelmann

Nemec

et al. 2020

J. Chem. Theory Comput.

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The Density-Functional Tight Binding (DFTB) method is a popular semiempirical approximation to Density Functional Theory (DFT). In many cases, DFTB can provide comparable accuracy to DFT at a fraction of the cost, enabling simulations on lengthand time-scales that are unfeasible with first principles DFT. At the same time (and in contrast to empirical interatomic potentials and force-fields), DFTB still offers direct access to electronic properties such as the band-structure. These advantages come at the cost of introducing empirical parameters to the method, leading to a reduced transferability compared to true first-principle approaches. Consequently, it would be very useful if the parameter-sets could be routinely adjusted for a given project.While fairly robust and transferable parameterization workflows exist for the electronic structure part of DFTB, the so-called repulsive potential V rep poses a major challenge.In this paper we propose a machine-learning (ML) approach to fitting V rep , using Gaussian Process Regression (GPR). The use of GPR circumvents the need for nonlinear or global parameter optimization, while at the same time offering arbitrary flexibility in terms of the functional form. We also show that the proposed method can be applied to multiple elements at once, by fitting repulsive potentials for organic molecules containing carbon, hydrogen and oxygen. Overall, the new approach removes focus from the choice of functional form and parameterization procedure, in favour of a data-driven philosophy.

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Universal tight binding model for chemical reactions in solution and at surfaces. II. Water

Lozovoi

Sheppard

Pashov

et al. 2014

The Journal of Chemical Physics

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Articles you may be interested inA revised water model intended for use in condensed phase simulations in the framework of the self consistent polarizable ion tight binding theory is constructed. The model is applied to water monomer, dimer, hexamers, ice, and liquid, where it demonstrates good agreement with theoretical results obtained by more accurate methods, such as DFT and CCSD(T), and with experiment. In particular, the temperature dependence of the self diffusion coefficient in liquid water predicted by the model, closely reproduces experimental curves in the temperature interval between 230 K and 350 K. In addition, and in contrast to standard DFT, the model properly orders the relative densities of liquid water and ice. A notable, but inevitable, shortcoming of the model is underestimation of the static dielectric constant by a factor of two. We demonstrate that the description of inter and intramolecular forces embodied in the tight binding approximation in quantum mechanics leads to a number of valuable insights which can be missing from ab initio quantum chemistry and classical force fields. These include a discussion of the origin of the enhanced molecular electric dipole moment in the condensed phases, and a detailed explanation for the increase of coordination number in liquid water as a function of temperature and compared with ice-leading to insights into the anomalous expansion on freezing. The theory holds out the prospect of an understanding of the currently unexplained density maximum of water near the freezing point. © 2014 AIP Publishing LLC.

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Universal tight binding model for chemical reactions in solution and at surfaces. III. Stoichiometric and reduced surfaces of titania and the adsorption of water

Cited by 5 publications

References 73 publications

Universal tight binding model for chemical reactions in solution and at surfaces. I. Organic molecules

Universal tight binding model for chemical reactions in solution and at surfaces. I. Organic molecules

Learning to Use the Force: Fitting Repulsive Potentials in Density-Functional Tight-Binding with Gaussian Process Regression

Universal tight binding model for chemical reactions in solution and at surfaces. II. Water

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