Chemically Accurate Excitation Energies With Small Basis Sets

10.26434/chemrxiv.8427116 ◽

2019 ◽

Author(s):

Emmanuel Giner ◽

Anthony Scemama ◽

Julien Toulouse ◽

Pierre-Francois Loos

Keyword(s):

Excited States ◽

Configuration Interaction ◽

Density Functional ◽

Chem Phys ◽

Basis Set ◽

Basis Sets ◽

Excitation Energies ◽

Functional Correction ◽

The One ◽

Range Density

By combining extrapolated selected configuration interaction (sCI) energies obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) algorithm with the recently proposed short-range density-functional correction for basis-set incompleteness [Giner et al., J. Chem. Phys. 2018, 149, 194301], we show that one can get chemically accurate vertical and adiabatic excitation energies with, typically, augmented double-ζ basis sets. We illustrate the present approach on various types of excited states (valence, Rydberg, and double excitations) in several small organic molecules (methylene, water, ammonia, carbon dimer and ethylene). The present study clearly evidences that special care has to be taken with very diffuse excited states where the present correction does not catch the radial incompleteness of the one-electron basis set.

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Low-Cost Molecular Excited States from a State-Averaged Resonating Hartree-Fock Approach

10.26434/chemrxiv.7871504 ◽

2019 ◽

Author(s):

Jacob Nite ◽

Carlos A. Jimenez-Hoyos

Keyword(s):

Excited States ◽

Configuration Interaction ◽

Low Cost ◽

Computational Cost ◽

Mean Field ◽

Chem Phys ◽

Spin Projection ◽

Excitation Energies ◽

Hartree Fock ◽

Orbital Relaxation

Quantum chemistry methods that describe excited states on the same footing as the ground state are generally scarce. In previous work, Gill et al. (J. Phys. Chem. A 112, 13164 (2008)) and later Sundstrom and Head-Gordon (J. Chem. Phys. 140, 114103 (2014)) considered excited states resulting from a non-orthogonal configuration interaction (NOCI) on stationary solutions of the Hartree–Fock equations. We build upon those contributions and present the state-averaged resonating Hartree–Fock (sa-ResHF) method, which differs from NOCI in that spin-projection and orbital relaxation effects are incorporated from the onset. Our results in a set of small molecules (alanine, formaldehyde, acetaldehyde, acetone, formamide, and ethylene) suggest that sa-ResHF excitation energies are a notable improvement over configuration interaction singles (CIS), at a mean-field computational cost. The orbital relaxation in sa-ResHF, in the presence of a spin-projection operator, generally results in excitation energies that are closer to the experimental values than the corresponding NOCI ones.

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Low-Cost Molecular Excited States from a State-Averaged Resonating Hartree-Fock Approach

10.26434/chemrxiv.7871504.v1 ◽

2019 ◽

Author(s):

Jacob Nite ◽

Carlos A. Jimenez-Hoyos

Keyword(s):

Excited States ◽

Configuration Interaction ◽

Low Cost ◽

Computational Cost ◽

Mean Field ◽

Chem Phys ◽

Spin Projection ◽

Excitation Energies ◽

Hartree Fock ◽

Orbital Relaxation

Quantum chemistry methods that describe excited states on the same footing as the ground state are generally scarce. In previous work, Gill et al. (J. Phys. Chem. A 112, 13164 (2008)) and later Sundstrom and Head-Gordon (J. Chem. Phys. 140, 114103 (2014)) considered excited states resulting from a non-orthogonal configuration interaction (NOCI) on stationary solutions of the Hartree–Fock equations. We build upon those contributions and present the state-averaged resonating Hartree–Fock (sa-ResHF) method, which differs from NOCI in that spin-projection and orbital relaxation effects are incorporated from the onset. Our results in a set of small molecules (alanine, formaldehyde, acetaldehyde, acetone, formamide, and ethylene) suggest that sa-ResHF excitation energies are a notable improvement over configuration interaction singles (CIS), at a mean-field computational cost. The orbital relaxation in sa-ResHF, in the presence of a spin-projection operator, generally results in excitation energies that are closer to the experimental values than the corresponding NOCI ones.

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Basis Set Effects in the Description of the Cl-O Bond in ClO and XClO/ClOX Isomers (X = H, O, and Cl) Using DFT and CCSD(T) Methods

Journal of Chemistry ◽

10.1155/2019/4057848 ◽

2019 ◽

Vol 2019 ◽

pp. 1-23 ◽

Cited By ~ 2

Author(s):

Kenneth Irving ◽

Martina Kieninger ◽

Oscar N. Ventura

Keyword(s):

Density Functional ◽

Basis Set ◽

Basis Sets ◽

Enthalpies Of Formation ◽

Isodesmic Reactions ◽

Dft Methods ◽

Functional Methods ◽

The One ◽

Isomeric Structures ◽

Different Sources

The performance of a group of density functional methods of progressive complexity for the description of the ClO bond in a series of chlorine oxides was investigated. The simplest ClO radical species and the two isomeric structures XClO/ClOX for each X = H, Cl, and O were studied using the PW91, TPSS, B3LYP, PBE0, M06, M06-2X, BMK, and B2PLYP functionals. Geometry optimizations and reaction enthalpies and enthalpies of formation for each species were calculated using Pople basis sets and the (aug)-cc-pVnZ Dunning sets, with n = D, T, Q, 5, and 6. For the calculation of enthalpies of formation, atomization and isodesmic reactions were employed. Both the precision of the methods with respect to the increase of the basis sets, as well as their accuracy, were gauged by comparing the results with the more accurate CCSD(T) calculations, performed using the same basis sets as for the DFT methods. The results obtained employing composite chemical methods (G4, CBS-QB3, and W1BD) were also used for the comparisons, as well as the experimental results when they are available. The results obtained show that error compensation is the key for successful description of molecular properties (geometries and energies) by carefully selecting the method and basis sets. In general, expansion of the one-electron basis set to the limit of completeness does not improve results at the DFT level, but just the opposite. The enthalpies of formation calculated at the CCSD(T)/aug-cc-pV6Z for the species considered are generally in agreement with experimental determinations and the most accurate theoretical values. Different sources of error in the calculations are discussed in detail.

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Basis Set Effects in the Description of the Cl-O Bond in ClO and XClO Isomers (X=H,O,Cl) Using DFT and CCSD(T) Methods

10.26434/chemrxiv.6135389 ◽

2018 ◽

Author(s):

Oscar Ventura ◽

Kenneth Irving ◽

Martina Kieninger

Keyword(s):

Density Functional ◽

Basis Set ◽

Basis Sets ◽

Enthalpies Of Formation ◽

Isodesmic Reactions ◽

Dft Methods ◽

Functional Methods ◽

The One ◽

Isomeric Structures ◽

Different Sources

The performance of a group of density functional methods of progressive complexity for the description of the ClO bond in a series of chlorine oxides was investigated. The simplest ClO radical species as well as the two isomeric structures XClO/ClOX for each X=H, Cl and O were studied using the PW91, TPSS, B3LYP, PBE0, M06, M06-2X, BMK and B2PLYP functionals. Geometry optimizations as well as reaction enthalpies and enthalpies of formation for each species were calculated using Pople basis sets and the (aug)-cc-pVnZ Dunning sets, with n=2-6. For the calculation of enthalpies of formation, atomization as well as isodesmic reactions were employed. Both the precision of the methods with respect to the increase of the basis sets, as well as their accuracy, were gauged by comparing the results with the more accurate CCSD(T) calculations, performed using the same basis sets as for the DFT methods. The results obtained employing composite chemical methods (G4, CBS-QB3 and W1BD) were also used for the comparisons, as well as the experimental results when they are available. The results obtained show that error compensation is the key for successful description of molecular properties (geometries and energies) by carefully selecting method and basis sets. In general, expansion of the one-electron basis set to the limit of completeness does not improve results at the DFT level, but just the opposite. The enthalpies of formation calculated at the CCSD(T)/aug-cc-pV6Z for the species considered are generally in agreement with experimental determinations, and the most accurate derived theoretically up to present. Different sources of error in the calculations are discussed in detail.

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Computing UV–vis spectra of 1-bromo-1-propene: a comparison of model core potential and all-electron basis sets

Canadian Journal of Chemistry ◽

10.1139/cjc-2016-0518 ◽

2017 ◽

Vol 95 (5) ◽

pp. 627-631 ◽

Cited By ~ 1

Author(s):

Meagan Oakley ◽

Mariusz Klobukowski

Keyword(s):

Excited States ◽

Density Functional ◽

Vacuum Ultraviolet ◽

Heavy Atom ◽

Basis Sets ◽

Excitation Energies ◽

Core Potential ◽

Td Dft ◽

Low Energies ◽

Potential Basis

Vacuum ultraviolet (VUV) spectroscopy can be used to identify different isomers in complicated mixtures of many molecules. In this work, calculated VUV spectra are compared with spectra of experimental mixtures to benchmark appropriate computational methods. Because the benchmark molecule, 1-bromo-1-propene, contains a heavy atom, both all-electron and model core potential basis sets were investigated. Time-dependent density functional theory (TD-DFT) can accurately compute electronic excited states at low-energy excitations and was cross-checked at higher energies against results from the symmetry adapted cluster–configuration interaction (SAC–CI) method. TD-DFT was determined to be satisfactory at low energies; however, excitation energies can deviate by 0.5 eV at high energies. TD-DFT with both all-electron and model core potential basis sets produced satisfactory excitation energies for the lower excited states. This method is also satisfactory at predicting spectra produced experimentally, including a mixture of isomers (cis- and trans-1-bromo-1-propene), with the exception of underestimating oscillator strength.

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Configuration interaction study of the electronic spectrum of methinophosphide, HCP

Canadian Journal of Physics ◽

10.1139/p90-078 ◽

1990 ◽

Vol 68 (6) ◽

pp. 499-507 ◽

Cited By ~ 13

Author(s):

S. P. Karna ◽

P. J. Bruna ◽

F. Grein

Keyword(s):

Excited States ◽

Configuration Interaction ◽

Basis Sets ◽

Spectroscopic Constants ◽

Stable States ◽

Excitation Energies ◽

Doubly Excited States ◽

Plane Component ◽

Doubly Excited ◽

State 1

Ab initio configuration interaction (CI) studies were performed on low-lying linear and nonlinear states of methinophosphide (HCP), using large basis sets with polarization and s, p Rydberg functions, and extensive multireference CI wave functions. Potential curves for linear states of HCP as functions of RCP and RCH and for nonlinear states as functions of αHCP were obtained, from which spectroscopic constants Te, Re, and ωe were evaluated. For the X1Σ+ ground state, the energy of dissociation into H + CP and the dipole moment were also calculated. The assignment of states based on the observed spectrum had to be revised in several instances. The ã state remained 13Σ+ (or 13A′), but the [Formula: see text] state became 13A″, the [Formula: see text] state, 13Δ, the Ã and [Formula: see text] states remained 11A″ and 21A′, respectively, [Formula: see text] was not seen as a seperate state, and [Formula: see text] became 13Σ−. In the energy range from 0 to 8 eV, 22 linear and 11 nonlinear stable states were found. Nonlinear states were stabilized for excitations from π(9a′, 2a″) into the in-plane component of π*, 10a′. Several doubly excited states of the type π2 → π*2 were bound, lying at relatively small excitation energies.

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An investigation of the excitation and emission properties of fluorescence compounds using DFT and TD-DFT methods

HUE UNIVERSITY JOURNAL OF SCIENCE NATURAL SCIENCE ◽

10.26459/hueuni-jns.v127i1a.4777 ◽

2018 ◽

Vol 127 (1A) ◽

pp. 43

Author(s):

Duong Tuan Quang

Keyword(s):

Density Functional Theory ◽

Excited States ◽

Density Functional ◽

Basis Set ◽

Excitation Energies ◽

Dft Methods ◽

Functional Theory ◽

Emission Properties ◽

Experimental Values ◽

Optimized Geometries

The density functional theory and time-dependent density functional theory methods were used for investigation of the excitation and emission properties of some fluorophores. The calculations were based on the optimized geometries of ground states and excited states at the B3LYP functional and LanL2DZ basis set. The results clarified the nature of the optical properties of the compounds and agreed well with the experimental data. The approximate values of excitation energies and emission energies of compounds were also identified. The calculated excitation energies were about 0.01 to 0.56 eV higher than experimental values. Meanwhile, the emission energies were from 0.34 to 0.89 eV higher than experimental values. These large errors occurred when there were great variations between the optimized geometries of ground state and excited states. They could be due to the presence of components of solvent in real solution that stabilized the excited states, leading to reduce the excitation and emission energies in the experiments.

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Basis Set Effects in the Description of the Cl-O Bond in ClO and XClO Isomers (X=H,O,Cl) Using DFT and CCSD(T) Methods

10.26434/chemrxiv.6135389.v1 ◽

2018 ◽

Cited By ~ 1

Author(s):

Oscar Ventura ◽

Kenneth Irving ◽

Martina Kieninger

Keyword(s):

Density Functional ◽

Basis Set ◽

Basis Sets ◽

Enthalpies Of Formation ◽

Isodesmic Reactions ◽

Dft Methods ◽

Functional Methods ◽

The One ◽

Isomeric Structures ◽

Different Sources

The performance of a group of density functional methods of progressive complexity for the description of the ClO bond in a series of chlorine oxides was investigated. The simplest ClO radical species as well as the two isomeric structures XClO/ClOX for each X=H, Cl and O were studied using the PW91, TPSS, B3LYP, PBE0, M06, M06-2X, BMK and B2PLYP functionals. Geometry optimizations as well as reaction enthalpies and enthalpies of formation for each species were calculated using Pople basis sets and the (aug)-cc-pVnZ Dunning sets, with n=2-6. For the calculation of enthalpies of formation, atomization as well as isodesmic reactions were employed. Both the precision of the methods with respect to the increase of the basis sets, as well as their accuracy, were gauged by comparing the results with the more accurate CCSD(T) calculations, performed using the same basis sets as for the DFT methods. The results obtained employing composite chemical methods (G4, CBS-QB3 and W1BD) were also used for the comparisons, as well as the experimental results when they are available. The results obtained show that error compensation is the key for successful description of molecular properties (geometries and energies) by carefully selecting method and basis sets. In general, expansion of the one-electron basis set to the limit of completeness does not improve results at the DFT level, but just the opposite. The enthalpies of formation calculated at the CCSD(T)/aug-cc-pV6Z for the species considered are generally in agreement with experimental determinations, and the most accurate derived theoretically up to present. Different sources of error in the calculations are discussed in detail.

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Benchmark of Simplified Time-Dependent Density Functional Theory for UV-Vis Spectral Properties of Porphyrinoids

10.26434/chemrxiv.9912860 ◽

2019 ◽

Author(s):

Kamal Batra ◽

Stefan Zahn ◽

Thomas Heine

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Large Scale ◽

Absolute Error ◽

Time Dependent ◽

Basis Set ◽

Basis Sets ◽

Functional Theory ◽

Framework Materials ◽

Dependent Density

We thoroughly benchmark time-dependent density- functional theory for the predictive calculation of UV/Vis spectra of porphyrin derivatives. With the aim to provide an approach that is computationally feasible for large-scale applications such as biological systems or molecular framework materials, albeit performing with high accuracy for the Q-bands, we compare the results given by various computational protocols, including basis sets, density-functionals (including gradient corrected local functionals, hybrids, double hybrids and range-separated functionals), and various variants of time-dependent density-functional theory, including the simplified Tamm-Dancoff approximation. An excellent choice for these calculations is the range-separated functional CAM-B3LYP in combination with the simplified Tamm-Dancoff approximation and a basis set of double-ζ quality def2-SVP (mean absolute error [MAE] of ~0.05 eV). This is not surpassed by more expensive approaches, not even by double hybrid functionals, and solely systematic excitation energy scaling slightly improves the results (MAE ~0.04 eV).

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