B3LYP Research Articles

Comparative Investigation of Pressure Effect on Structural Stability, Electronic and Optical Response of LaXO<sub>3</sub> (X = Al, In, Ga) for Optoelectronic Applications

A first principle study intense on the density functional theory with Heydscuseria-Ernzerhof screened hybrid functional hybrid function (HSEO6) is used to assess the structural, Electronic, elastic, mechanical and optical responses of LaXO<sub>3</sub> (X = Al, In, Ga) perovskite materials. The compressive investigation under the external static isotropic pressure (P= 0 to 80GaP), phase stability, band structure and their important impact on the optical response of LaAlO<sub>3</sub>, LaInO<sub>3</sub> and LaGaO<sub>3</sub>. Electronic band structure shows that LaXO<sub>3</sub> (X = Al, In Ga) semiconductor with indirect band gap and an optically inactive response up to 20GPa, while the band gap becomes direct at 80GaP. There are gamma points (G-X-Q) at 80GPa and the band gap changes from indirect to direct nature. Under main desperation physical parameters of perovskite materials are well explained the response of TDOS, PDOS and EPDOS contour plots have been well understood for the full description of the band gap. It is further observed that the external pressure enhanced upto 40GPa both materials are significantly more mechanically stable compared to pristine LaXO<sub>3</sub> (X = Al, In, Ga) at 0GPa. The optical properties of LaAlO<sub>3</sub>, LaGaO<sub>3 </sub>and LaInO<sub>3</sub>, dielectric coefficient <i>(ε<sub>1</sub>, iε<sub>2</sub>)</i> have been employed along with the optical responses like absorption, energy loss function, reflectivity and reflective index are obtained in the energy scale from 0 to 60 eV. It was observed that static dielectric constant decreases with the decrease in optical band gap. The optical tunings under the effect of pressure which are good candidates in practical optoelectronic applications are extensively used and interpreted by the calculation of the dielectric function.

Hybrid functionals with nonempirical Hartree-Fock parameters for electronic structure calculation of layered oxides

Hybrid functionals with nonempirical Hartree-Fock parameters for electronic structure calculation of layered oxides

MODELING OF THE ELECTRONIC AND ELASTIC PROPERTIES OF THE Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub> CRYSTAL

In this scientific work, we conducted a comprehensive study of yttrium aluminum garnet using computer modeling methods. Our efforts are focused on the precise analysis of elastic properties, the development of equations of state, as well as a detailed study of crystal and band structures. We conducted a detailed study of the mechanical parameters of the material, such as the modulus of elasticity and the Poisson's ratio, using modern computational methods. Virtual modeling methods allow us to study in detail the mechanical characteristics of the material. The main focus is on the creation and verification of computer models that accurately reflect the elastic properties of the crystal. The values obtained using various hybrid functionals were compared with experimental data. Virtual models allowed not only to study in detail the mechanical characteristics of the material, but also provided results that are significantly close to real experimental data. Comparisons were carried out according to the following parameters: cell parameters, band gap energy, effective charges of crystal atoms, equations of state and elastic properties. Also, the error levels relative to the experimental data are determined. We present the results of the analysis of the crystal structure of yttrium aluminum garnet achieved using various exchange-correlation hybrid functionals such as B3PW, B3LYP, HSE06, PBE. This aspect of the study includes the analysis of the crystal lattice parameters, the distribution of atoms in the crystal and the band structure, which is important for a complete understanding of the properties of the material.

Native point defects in HgCdTe infrared detector material: Identifying deep centers from first principles

We investigate the native point defects in the long-wavelength infrared (LWIR) detector material Hg0.75Cd0.25Te using a dielectric-dependent hybrid density functional combined with spin–orbit coupling. Characterizing these point defects is essential as they are responsible for intrinsic doping and nonradiative recombination centers in the detector material. The dielectric-dependent hybrid functional allows for an accurate description of the bandgap (Eg) for Hg1−xCdxTe (MCT) over the entire compositional range, a level of accuracy challenging with standard hybrid functionals. Our comprehensive examination of the native point defects confirms that cation vacancies VHg(Cd) are the primary sources of p-type conductivity in the LWIR material given their low defect formation energies and the presence of a shallow acceptor level (−/0) near the valence-band maximum. In addition to the shallow acceptor level, the cation vacancies exhibit a deep charge transition level (2−/−) situated near the midgap, characteristic of nonradiative recombination centers. Our results indicate that Hg interstitial could also be a deep center in the LWIR MCT through a metastable configuration under the Hg-rich growth conditions. While an isolated Te antisite does not show deep levels, the formation of VHg–TeHg defect complex introduces a deep acceptor level within the bandgap.

Automated all-functionals infrared and Raman spectra

AbstractInfrared and Raman spectroscopies are ubiquitous techniques employed in many experimental laboratories, thanks to their fast and non-destructive nature able to capture materials’ features as spectroscopic fingerprints. Nevertheless, these measurements frequently need theoretical and computational support in order to unambiguously decipher and assign complex spectra. Linear-response theory provides an effective way to obtain the higher-order derivatives needed, but its applicability to modern exchange-correlation functionals and pseudopotential formalism remains limited. Here, we devise an automated, open-source, user-friendly approach based on density-functional theory and the electric-enthalpy functional to allow seamless calculation from first principles of infrared absorption and reflectivity, together with zone-center phonons, static dielectric tensor, and Raman spectra. By employing a finite-displacement and finite-field approach, we allow for the use of any functional, as well as an efficient treatment of large low-symmetry structures. Additionally, we propose a simple scheme for efficiently sampling the Brillouin zone at different electric fields. To demonstrate the capabilities of the present approach, we study ferroelectric LiNbO3 crystal as a paradigmatic example, and predict infrared and Raman spectra using various (semi)local, Hubbard corrected, and hybrid functionals. Our results also show how PBE0 and extended Hubbard functionals (PBEsol+U+V) yield for this case the best match in term of peak positions and intensities, respectively.

Undoing band anticrossing in highly mismatched alloys by atom arrangement

The electronic structures of three highly mismatched alloys (HMAs)—GeC(Sn), Ga(In)NAs, and BGa(In)As—were studied using density functional theory with HSE06 hybrid functionals, with an emphasis on the local environment near the mismatched, highly electronegative atom (B, C, and N). These alloys are known for their counterintuitive reduction in the bandgap when adding the smaller atom, due to a band anticrossing (BAC) or splitting of the conduction band. Surprisingly, the existence of band splitting was found to be completely unrelated to the local displacement of the lattice ions near the mismatched atom. Furthermore, in BGaAs, the reduction in the bandgap due to BAC was weaker than the increase due to the lattice constant, which has not been observed among other HMAs but may explain differences among experimental reports. While local distortion in GeC and GaNAs was not the cause for BAC, it was found to enhance the bandgap reduction due to BAC. This work also found that mere contrast in electronegativity between neighboring atoms does not induce BAC. In fact, surrounding the electronegative atom with elements of even smaller electronegativity than the host (e.g., Sn or In) consistently decreased or even eliminated BAC. For a fixed composition, moving Sn toward C and In toward either N or B was always energetically favorable and increased the bandgap, consistent with experimental annealing results. Such rearrangement also delocalized the conduction band wavefunctions near the mismatched atom to resemble the original host states in unperturbed Ge or GaAs, causing the BAC to progressively weaken. These collective results were consistent whether the mismatched atom was a cation (N), anion (B), or fully covalent (C), varying only with the magnitude of its electronegativity, with B having the least effect. The effects can be explained by charge screening of the mismatched atom's deep electrostatic potential. Together, these results help explain differences in the bandgap and other properties reported for HMAs from different groups and provide insight into the creation of materials with designer properties.

Performance of Density Functionals for Excited-State Properties of Isolated Chromophores and Exciplexes: Emission Spectra, Solvatochromic Shifts, and Charge-Transfer Character.

This study assesses the performance of various meta-generalized gradient approximation (meta-GGA), global hybrid, and range-separated hybrid (RSH) density functionals in capturing the excited-state properties of organic chromophores and their excited-state complexes (exciplexes). Motivated by their uses in solar energy harvesting and photoredox CO2 reduction, we use oligo-(p-phenylenes) and their excited-state complexes with triethylamine as model systems. We focus on the fluorescence properties of these systems, specifically emission energies. We also consider solvatochromic shifts and wave function characteristics. The latter is described by using reduced quantities such as natural transition orbitals (NTOs) and exciton descriptors. The functionals are benchmarked against the experimental fluorescence spectra and the equation-of-motion coupled-cluster method with single and double excitations. Both in isolated chromophores and in exciplexes, meta-GGA functionals drastically underestimate the emission energies and exhibit significant exciton delocalization and anticorrelation between electron and hole motion. The performance of global hybrid functionals is strongly dependent on the percentage of exact exchange. Our study identifies RSH GGAs as the best-performing functionals, with ωPBE demonstrating the best agreement with experimental results. RSH meta-GGAs often overestimate emission energies in exciplexes and yield larger hole NTOs. Their performance can be improved by optimally tuning the range-separation parameter.

Theoretical exploration of the stabilities and detonation parameters of nitro-substituted 1H-benzotriazole.

The nitro group was introduced into the nitrogen heterocycle of 1H-benzotriazole to design a total of 31 derivatives. To estimate the thermal stability of these derivatives, the heat of formation (HOF) is calculated based on the isodesmic reaction. The bond dissociation energy (BDE) was also predicted based on the homolytic reaction to further evaluate the dynamic stability. To evaluate the possibility of utilizing as high energy density compounds (HEDCs), the detonation parameters including the detonation pressure (P), detonation velocity (D), and explosive heat (Q) are predicted by taking advantage of the Kamlet-Jacobs empirical equation. To measure the sensitivity to impact, both the characteristic height (H50) and free space in crystal (∆V) are considered in this paper. Based on our calculations, D-series and E are found to be the candidates for HEDCs. The Gaussian 09 software package was used in this paper. The B3PW91 hybrid function with the 6-311 + G(d,p) basis set was chosen to perform the structural optimization, frequency analysis, heat of formation, and bond dissociation energy. The detonation parameters were calculated following the Kamlet-Jacobs equation.

Basis Set Requirements of σ-Functionals for Gaussian- and Slater-Type Basis Functions and Comparison with Range-Separated Hybrid and Double Hybrid Functionals.

σ-Functionals belong to the class of Kohn-Sham (KS) correlation functionals based on the adiabatic-connection fluctuation-dissipation theorem and are technically closely related to the random phase approximation (RPA). They have the same computational demand as the latter, with the computational effort of an energy evaluation for both methods being lower than that of a preceding hybrid DFT calculation for typical systems but yield much higher accuracy, reaching chemical accuracy of 1 kcal/mol for quantities such as reactions and transition energies in main group chemistry. In previous work on σ-functionals, rather large Gaussian basis sets have been used. Here, we investigate the actual basis set requirements of σ-functionals and present three setups that employ smaller Gaussian basis sets ranging from quadruple-ζ (QZ) to triple-ζ (TZ) quality and represent a good compromise between accuracy and computational efficiency. Furthermore, we introduce an implementation of σ-functionals based on Slater-type basis sets and present two setups of QZ and TZ quality for this implementation. We test the accuracy of these setups on a large database of various physical properties and types of reactions, as well as equilibrium geometries and vibrational frequencies. As expected, the accuracy of σ-functional calculations becomes somewhat lower with a decreasing basis set size. However, for all setups considered here, calculations with σ-functionals are clearly more accurate than those within the RPA and even more so than those of the conventional KS methods. For the smallest setup using Gaussian-type basis functions and Slater-type basis functions, we introduce a reparametrization that reduces the loss in accuracy due to the basis set error to some extent. A comparison with the range-separated hybrid ωB97X-V and the double hybrid DSD-BLYP-D3 shows that σ functionals outperform in accuracy both of these accurate and, for their class, representative functionals.

Implementation and First Evaluation of Strong-Correlation-Corrected Local Hybrid Functionals for the Calculation of NMR Shieldings and Shifts.

Local hybrid functionals containing strong-correlation factors (scLHs) and range-separated local hybrids (RSLHs) have been integrated into an efficient coupled-perturbed Kohn-Sham implementation for the calculation of nuclear shielding constants. Several scLHs and the ωLH22t RSLH have then been evaluated for the first time for the extended NS372 benchmark set of main-group shieldings and shifts and the TM70 benchmark of 3d transition-metal shifts. The effects of the strong-correlation corrections have been analyzed with respect to the spatial distribution of the sc-factors, which locally diminish exact-exchange admixture at certain regions in a molecule. The scLH22t, scLH23t-mBR, and scLH23t-mBR-P functionals, which contain a "damped" strong-correlation factor to retain the excellent performance of the underlying LH20t functional for weakly correlated situations, tend to make smaller corrections to shieldings and shifts than the "undamped" scLH22ta functional. While the latter functional can also deteriorate agreement with the reference data in certain weakly correlated cases, it provides overall better performance, in particular for systems where static correlation is appreciable. This pertains only to a minority of systems in the NS372 main-group test set but to many more systems in the TM70 transition-metal test set, in particular for high-oxidation-state complexes, e.g., Cr(+VI) complexes and other systems with stretched bonds. Another undamped scLH, the simpler LDA-based scLH21ct-SVWN-m, also tends to provide significant improvements in many cases. The differences between the functionals and species can be rationalized on the basis of one-dimensional plots of the strong-correlation factors, augmented by isosurface plots of the fractional orbital density (FOD). Position-dependent exact-exchange admixture is thus shown to provide substantial flexibility in treating response properties like NMR shifts for both weakly and strongly correlated systems.

The performance and efficiency of twelve range-separated hybrid DFT functionals for calculation of the magnetic exchange coupling constants of di-nuclear first row transition metal complexes

The performance and efficiency of twelve range-separated hybrid functionals are compared with each other in calculating magnetic exchange coupling constant (J) data on eleven di-nuclear first-row transition metal complexes having di-copper (Cu) and di-vanadium (V) as their central atoms. The J values are then compared with the experimental findings. In addition to that we also computed the B3LYP results of these complexes. We compared them with the results obtained from range-separated functionals as well as with the experimental results to understand their performances in predicting the magnetic exchange coupling constant. When computing, we reoptimized all the structures of the complexes taken from the crystal data, and then the values of Js were determined. The performances are predicted in terms of four statistical error matrices, namely, the mean absolute error (MAE), mean fractional error (MFE), mean signed error (MSE), root mean square error (RMSE) in cm−1.

Transition Metal Impurities as Shallow Donors in β‐Ga2O3

An in‐depth investigation of transition metal impurities (Hf, Zr, Nb, and W) is presented as shallow donors in monoclinic Ga2O3 using first‐principles calculations within the framework of density functional theory. A combination of semilocal and hybrid functionals is used to predict their binding energies and hyperfine parameters. The generalized gradient approximation (GGA) allows performing calculations for supercells of up to 2500 atoms, enabling an extrapolation to the dilute limit. The shortcoming of GGA in correctly describing the electron localization is then overcome by the use of the hybrid functional. Results are presented and discussed in light of the application of these transition‐metal elements as shallow donors in Ga2O3 and their identification in the experiment. The methodology applied here can be used in calculations for shallow donors in other systems.

Spin-Symmetry Breaking and Hyperfine Couplings in Transition-Metal Complexes Revisited Using Density Functionals Based on the Exact-Exchange Energy Density.

A small set of mononuclear manganese complexes evaluated previously for their Mn hyperfine couplings (HFCs) has been analyzed using density functionals based on the exact-exchange energy density─in particular, the spin symmetry breaking (SSB) found previously when using hybrid functionals. Employing various strong-correlation corrected local hybrids (scLHs) and strong-correlation corrected range-separated local hybrids (scRSLHs) with or without additional corrections to their local mixing functions (LMFs) to mitigate delocalization errors (DE), the SSB and the associated dipolar HFCs of [Mn(CN)4]2-, MnO3, [Mn(CN)4N]-, and [Mn(CN)5NO]2- (the latter with cluster embedding) have been examined. Both strong-correlation (sc)-correction and DE-correction terms help to diminish SSB and correct the dipolar HFCs. The DE corrections are more effective, and the effects of the sc corrections depend on their damping factors. Interestingly, the DE-corrections reduce valence-shell spin polarization (VSSP) and thus SSB by locally enhancing exact-exchange (EXX) admixture near the metal center and thereby diminishing spin-density delocalization onto the ligand atoms. In contrast, sc corrections diminish EXX admixture locally, mostly on specific ligand atoms. This then reduces VSSP and SSB as well. The performance of scLHs and scRSLHs for the isotropic Mn HFCs has also been analyzed, with particular attention to core-shell spin-polarization contributions. Further sc-corrected functionals, such as the KP16/B13 construction and the DM21 deep-neural-network functional, have been examined.

Polymorphs of Copper Zinc Tin Sulfide: Optoelectronic Properties and Detection Using Raman

Despite its growing popularity as a solar material, there is no comprehensive reference to aid with determining various polymorphs of copper zinc tin sulfide (CZTS) in the lab. Understanding the diverse electronic, optical and vibrational properties of these polymorphs is crucial to further enhance the conversion efficiency of CZTS solar cells. Here, findings are presented that suggest the effective hole mass in a monoclinic polymorph, that is likely to form along with the more commonly reported tetragonal variations, is about 10 times heavier than that of its tetragonal counterparts, thereby affecting key attributes such as carrier transport and concentration. Among tetragonal polymorphs, the so‐called primitive mixed CuAu (PMCA) arrangement is likely to undergo a direct‐indirect gap transition due to internal strains. Optical absorption between different polymorphs could also vary by up to 90% in the visible spectrum. Finally, accurate Raman footprint of each polymorph is predicted to help establish a definitive method for their detection. From a modeling perspective, Becke‐Lee‐Yang‐Parr with spin‐orbit coupling is shown to be a superior yet 100X faster alternative to hybrid functionals when applied to studying electronic structure of CZTS.

Photoredox matching of earth-abundant photosensitizers with hydrogen evolving catalysts by first-principles predictions.

Photoredox properties of several earth-abundant light-harvesting transition metal complexes in combination with cobalt-based proton reduction catalysts have been investigated computationally to assess the fundamental viability of different photocatalytic systems of current experimental interest. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations using several GGA (BP86, BLYP), hybrid-GGA (B3LYP, B3LYP*), hybrid meta-GGA (M06, TPSSh), and range-separated hybrid (ωB97X, CAM-B3LYP) functionals were used to calculate relevant ground and excited state reduction potentials for photosensitizers, catalysts, and sacrificial electron donors. Linear energy correction factors for the DFT/TD-DFT results that provide the best agreement with available experimental reference results were determined in order to provide more accurate predictions. Among the selection of functionals, the B3LYP* and TPSSh sets of correction parameters were determined to give the best redox potentials and excited states energies, ΔEexc, with errors of ∼0.2eV. Linear corrections for both reduction and oxidation processes significantly improve the predictions for all the redox pairs. In particular, for TPSSh and B3LYP*, the calculated errors decrease by more than 0.5V against experimental values for catalyst reduction potentials, photosensitizer oxidation potentials, and electron donor oxidation potentials. Energy-corrected TPSSh results were finally used to predict the energetics of complete photocatalytic cycles for the light-driven activation of selected proton reduction cobalt catalysts. These predictions demonstrate the broader usefulness of the adopted approach to systematically predict full photocycle behavior for first-row transition metal photosensitizer-catalyst combinations more broadly.

A Density Functional Theory Insight into Structural, Mechanical, and Optical Properties of Rb2LiTlF6 Double Perovskite

The density functional theory (DFT) is applied to systematically investigate the geometrical structure, electronic, mechanical, vibrational, and optical properties of double perovskite Rb2LiTlF6 in its cubic phase. To the best of one's knowledge, many physical properties of this compound are still not well established or not yet investigated; such as phonon properties, mechanical behavior, thermal properties, and so on. In this work, the stability of Rb2LiTlF6 is explored by looking at its thermodynamical behavior through calculation of formation energy, cohesive energy, Goldschmidt tolerance factor, and phonon dispersion. Its mechanical properties are examined based on various characterization descriptors such as the independent elastic coefficients, bulk, shear, and Young's modulus, ratios such as Pugh and Poisson's, Kleinnman parameter, Zener anisotropy factor, Debye temperature, and melting temperature. Sound velocity in this material is predicted from the values of the bulk and shear modulus obtained. Thermal expansion coefficient at finite temperatures are obtained using the approach of quasi‐harmonic approximation. Its electronic property is also investigated using generalized gradient approximation and also hybrid functionals. At a later stage, its optical behavior upon the effect of light excitation is explored using the many body pertubation theory approximation. Having envisioned this material as a wide band gap semiconductor, it can be useful in numerous applications such as designing the top‐cell of tandem photovoltaic configuration, photodetection, and light emitting diodes. It is strongly believed that this work will provide a helpful guidance for future experimental and theoretical investigations of this material.

TD‐DFT analysis of the excitation of H‐dimers of cationic dyes in an aqueous solution using functionals without additional dispersion correction

AbstractThis work is a development and extension of the previous one (DOI: 10.1039/d3cp00882g). Here, H‐dimers of acridine (acridine orange—AO and proflavine—PF), thiazine (methylene blue—MB and thionine—TH), and oxazine (brilliant cresyl blue—BCB and Nile blue—NB) dyes were modeled using hybrid functionals with a large proportion of exact Hartree–Fock exchange and long‐range correction. It turned out that nine functionals (LC‐ωHPBE, M06HF, M052X, M062X, M08HX, M11, MN15, SOGGA11X, and ωB97XD) reliably stabilize these molecular aggregates in both the ground and excited states. In addition, these functionals ensure that the conditions for transition moments (M(dimer) ≈ M(monomer) from strong coupling theory for H‐aggregates) and absorption maxima (λmax(dimer) < λmax(monomer) from Kasha exciton theory) are met. The S2 excited state stabilizes the H‐dimers more strongly than the ground state, while the S1 state stabilizes even more than S2. This is due to the large overlap between the corresponding molecular orbitals (LUMO > HOMO−1 > HOMO). When calculating the vibronic absorption spectra, the best agreement with the experiment for AO2, PF2, and NB2 showed the M08HX functional, and M11—for MB2 and BCB2. For dye monomers, these functionals gave the worst agreement, and MN15 demonstrated the closest similarity to the experiment. Vibronic absorption spectra for AO2, MB2, BCB2, and NB2 were calculated for the first time. The exciton splitting is calculated, which for MB2 is in good agreement with the experimental value.

Ab Initio Study on the Vibrational and Electronic Properties of Radiation-Induced Defects in Potassium Bromide

The vibrational and electronic properties of several basic radiation defects in potassium bromide are computed at the quantum mechanical level using a periodic supercell approach based on hybrid functionals, an all-electron Gaussian-type basis set, and the Crystalcomputer code. The exciton energy in alkali halides is sufficient to create lattice defects, such as F–H Frenkel defect pairs, resulting in a relatively high concentration of single defects and their complexes. Here, we consider eight defects: the electronic F+- and F-centers (bromine vacancy without and with trapped electrons) and their dimers; hole H-center (neutral bromine atom forming the dumbbell ion with a regular Br− ion.); VK-center (Br2− molecular ion consisting of a hole and two regular ions); and two complex Br3− defects, combinations of several simple defects. The local geometry and the charge- and spin-density distributions of all defects are analyzed. Every defect shows its characteristic features in Raman spectra, and their comparison with available experimental data is discussed.

Electronic Structure of Metalloporphenes, Antiaromatic Analogues of Graphene.

Zinc porphene is a two-dimensional material made of fully fused zinc porphyrins in a tetragonal lattice. It has a fully conjugated π-system, making it similar to graphene. Zinc porphene has recently been synthesized, and a combination of rough conductivity measurements and infrared and Raman spectroscopies all suggested that it is a semiconductor (Magnera, T.F. et al. Porphene and Porphite as Porphyrin Analogs of Graphene and Graphite, Nat. Commun.2023, 14, 6308). This is in contrast with all previous predictions of its electronic structure, which indicated metallic conductivity. We show that the gap-opening in zinc porphene is caused by a Peierls distortion of its unit cell from square to rectangular, thus giving the first account of its electronic structure in agreement with the experiment. Accounting for this distortion requires proper treatment of electron delocalization, which can be done using hybrid functionals with a substantial amount of exact exchange. Such a functional, PBE38, is then applied to predict the properties of many first transition row metalloporphenes, some of which have already been prepared. We find that changing the metal strongly affects the electronic structure of metalloporphenes, resulting in a rich variety of both metallic conductors and semiconductors, which may be of great interest to molecular electronics and spintronics. Properties of these materials are mostly governed by the extent of the Peierls distortion and the number of electrons in their π-system, analogous to changes in aromaticity observed in cyclic conjugated molecules upon oxidation or reduction. These results give an account of how the concept of antiaromaticity can be extended to periodic systems.

Single-Pole Polarization Models: Rapid Evaluation of Electron Affinities of Solvated-Electron and Superatomic Molecular Anionic States.

We propose a single-parameter effective one-particle potential, termed the single-pole exchange-correlation (1p-XC), to rapidly evaluate electron affinities (EAs) of nonvalence electronic states of molecular clusters and nanoassemblies. The model combines exact-exchange and the random phase approximation (RPA) correlation potential with a single-pole approximation to model the frequency-dependent polarization function. It captures long-range static and dynamic-frequency effects in the correlation potential, with mean absolute errors of 0.06 eV for EAs of hydrated- and ammoniated-electron clusters with EA values in the range 0.24-1.77 eV. The 1p-XC approximation enables EA estimation with a computational wall-time similar to that of hybrid functionals. The model also provides a compressed-basis, which significantly reduces the rank of higher-level parameter-free one-particle Hamiltonians and further simplifies the computation of EAs. The compressed-basis approach is used to model the hybridization of superatomic molecular states of (C60)2- and (C60)3-, thereby verifying previous model Hamiltonian studies.