First-Principles Photoemission Spectroscopy and Orbital Tomography in Molecules from Koopmans-Compliant Functionals

Nguyen, Ngoc Linh; Borghi, Giovanni; Ferretti, Andrea; Dabo, Ismaïla; Marzari, Nicola

doi:10.1103/physrevlett.114.166405

Cited by 45 publications

(75 citation statements)

References 75 publications

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“…This approach, elaborated further below, was shown to yield excellent fundamental and optical gaps for molecules [42,43]. More recently, it has been generalized so as to provide accurate single-particle excitations for both molecules [44][45][46] and molecular crystals [38,47], and it was shown to capture gap renormalization in molecular solids [38]. Can this approach, then, resolve the long-standing challenge of providing an accurate one-and two-particle excitation spectrum in solid-state systems fully within the framework of (TD)DFT?…”

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confidence: 99%

Solid-state optical absorption from optimally tuned time-dependent range-separated hybrid density functional theory

et al. 2015

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We present a framework for obtaining reliable solid-state charge and optical excitations and spectra from optimally-tuned range-separated hybrid density functional theory. The approach, which is fully couched within the formal framework of generalized Kohn-Sham theory, allows for accurate prediction of exciton binding energies. We demonstrate our approach through first principles calculations of one-and two-particle excitations in pentacene, a molecular semiconducting crystal, where our work is in excellent agreement with experiments and prior computations. We further show that with one adjustable parameter, set to produce an accurate bandgap, this method accurately predicts band structures and optical spectra of silicon and lithium flouride, prototypical covalent and ionic solids. Our findings indicate that for a broad range of extended bulk systems, this method may provide a computationally inexpensive alternative to many-body perturbation theory, opening the door to studies of materials of increasing size and complexity.

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confidence: 99%

Solid-state optical absorption from optimally tuned time-dependent range-separated hybrid density functional theory

et al. 2015

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“…(10) More details on the calculation of I (ν) can be found in Ref. 36. The excitation energy is now expressed in terms of the kinetic energy 2 k 2 /2m of the ejected electron and its binding energy E b i defined as the negative of the Dyson orbital energy ε d i .…”

Section: Ultraviolet Photoemission Spectroscopymentioning

confidence: 99%

“…In previous work 28,29,31,32,36 the calculation of α (v) was performed at fixed geometry, assuming the variation of the screening during the geometry optimization to be negligible. In this work we explore self-consistency for α (v) with respect to molecular geometry.…”

Section: Geometry and Screening Optimizationmentioning

confidence: 99%

“…This PWL condition is a generalization to the entire manifold of the molecular DFT+U approach 33,34 , stemming from similar linearization ideas in the solid state. 35 The condition of Koopmans' compliance is naturally akin to that of enforcing a correct description of charged excitations 28,36 , and can therefore lead to orbital energies that are comparable to the quasiparticle excitation energies of photoemission experiments. In a previous work 36 , we showed the remarkable performance of KC functionals in predicting ultraviolet photoemission spectra (UPS) and orbital tomography momentum maps for photovoltaic molecules, showing an agreement with experiments for frontier orbital energies [ionization potentials (IPs) and electron affinities (EAs)] that is comparable (in some cases even slightly superior) to state-of-the-art methods in many-body perturbation theory, while preserving a moderate computational cost and scaling 32 , and the quality of potential energy surfaces of the underlying DFT functionals 32 .…”

Section: Introductionmentioning

confidence: 99%

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First-Principles Photoemission Spectroscopy of DNA and RNA Nucleobases from Koopmans-Compliant Functionals

Nguyen

Borghi

Ferretti

et al. 2016

J. Chem. Theory Comput.

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The need to interpret ultraviolet photoemission data strongly motivates the refinement of firstprinciples techniques able to accurately predict spectral properties. In this work we employ Koopmans-compliant functionals, constructed to enforce piecewise linearity in approximate density functionals, to calculate the structural and electronic properties of DNA and RNA nucleobases. Our results show that not only ionization potentials and electron affinities are accurately predicted with mean absolute errors < 0.1 eV, but also that calculated photoemission spectra are in excellent agreement with experimental ultraviolet photoemission spectra. In particular, the role and contribution of different tautomers to the photoemission spectra are highlighted and discussed in detail. The structural properties of nucleobases are also investigated, showing an improved description with respect to local and semilocal density-functional theory. Methodologically, our results further consolidate the role of Koopmans-compliant functionals in providing, through orbital-density-dependent potentials, accurate electronic and spectral properties.

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“…Note that while the two issues are related in a physical sense, they are not the same and their connection in the construction of reasonable DFAs is far less obvious [34]. Another shortcoming affecting the KS eigenvalues is the deviation of the total energy curve, E(N ), as a function of the number of electrons, N , from piecewise linearity, for fractional N (see, e.g., [14,[35][36][37][38][39][40][41][42][43][44][45][46][47][48]). In the literature, this phenomenon is sometimes referred to as many-electron self-interaction [35][36][37]39] or as a (de-)localization error [38,41,46].…”

Section: Introductionmentioning

confidence: 99%

Effect of ensemble generalization on the highest-occupied Kohn-Sham eigenvalue

Kraisler

Schmidt

Kümmel

et al. 2015

The Journal of Chemical Physics

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There are several approximations to the exchange-correlation functional in density-functional theory that accurately predict total energy-related properties of many-electron systems, such as binding energies, bond lengths, and crystal structures. Other approximations are designed to describe potential-related processes, such as charge transfer and photoemission. However, the development of a functional which can serve the two purposes simultaneously is a long-standing challenge. Trying to address it, we employ in the current work the ensemble generalization procedure proposed in Phys. Rev. Lett. 110, 126403 (2013). Focusing on the prediction of the ionization potential via the highest occupied Kohn-Sham eigenvalue, we examine a variety of exchange-correlation approximations: the local spin-density approximation, semi-local generalized gradient approximations, and global and local hybrid functionals. Results for a test set of 26 diatomic molecules and single atoms are presented. We find that the aforementioned ensemble generalization systematically improves the prediction of the ionization potential, for various systems and exchange-correlation functionals, without compromising the accuracy of total energy-related properties. We specifically examine hybrid functionals. These depend on a parameter controlling the ratio of semi-local to non-local functional components. The ionization potential obtained with ensemble-generalized functionals is found to depend only weakly on the parameter value, contrary to common experience with non-generalized hybrids, thus eliminating one aspect of the so-called 'parameter dilemma' of hybrid functionals.

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First-Principles Photoemission Spectroscopy and Orbital Tomography in Molecules from Koopmans-Compliant Functionals

Cited by 45 publications

References 75 publications

Solid-state optical absorption from optimally tuned time-dependent range-separated hybrid density functional theory

Solid-state optical absorption from optimally tuned time-dependent range-separated hybrid density functional theory

First-Principles Photoemission Spectroscopy of DNA and RNA Nucleobases from Koopmans-Compliant Functionals

Effect of ensemble generalization on the highest-occupied Kohn-Sham eigenvalue

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