Gaussian Orbital Calculations Research Articles

GW100: A Plane Wave Perspective for Small Molecules.

In a recent work, van Setten and co-workers have presented a carefully converged G0W0 study of 100 closed shell molecules [ J. Chem. Theory Comput. 2015 , 11 , 5665 - 5687 ]. For two different codes they found excellent agreement to within a few 10 meV if identical Gaussian basis sets were used. We inspect the same set of molecules using the projector augmented wave method and the Vienna ab initio simulation package (VASP). For the ionization potential, the basis set extrapolated plane wave results agree very well with the Gaussian basis sets, often reaching better than 50 meV agreement. In order to achieve this agreement, we correct for finite basis set errors as well as errors introduced by periodically repeated images. For positive electron affinities differences between Gaussian basis sets and VASP are slightly larger. We attribute this to larger basis set extrapolation errors for the Gaussian basis sets. For quasi particle (QP) resonances above the vacuum level, differences between VASP and Gaussian basis sets are, however, found to be substantial. This is tentatively explained by insufficient basis set convergence of the Gaussian type orbital calculations as exemplified for selected test cases.

Helium Dimer Interaction Energies from Gaussian Geminal and Orbital Calculations

Nonrelativistic clamped nuclei interaction energies for a pair of helium atoms have been computed using the Gaussian geminal implementation of the coupled cluster theory with single and double excitations (CCSD). Effects of triple and quadruple excitations were subsequently included employing the conventional orbital approach and very large augmented, correlation-consistent bases extended by sets of bond functions. Up to the coupled cluster doubles (CCD) level, the Gaussian geminal expansions provide nearly an order of magnitude better accuracy than orbital expansions even if the latter results are extrapolated. The recommended values of the helium dimer interaction energy are 292.54 ± 0.04 K, −11.009 ± 0.008 K, and −4.619 ± 0.007 K at the interatomic distances equal to 4.0, 5.6, and 7.0 bohr, respectively. The major contributions to the error estimates come from the orbital parts of the calculations beyond the CCSD level.

Photodissociation dynamics of S4N4 at 222 and 248 nm

Emission from several electronically excited states of NS is observed when the energetic molecule S4N4 is photolyzed with radiation from an excimer laser. Photolysis at 248 nm generates fluorescence from the B 2Π1/2,3/2, H 2Π1/2, G 2Σ−, and I 2Σ+ states of NS. NS(B 2Π1/2,3/2) and NS(C 2Σ+) fluorescence is observed when the photolysis wavelength is changed to 222 nm. The NS(H) and NS(C) spectra are postulated to arise from a resonant interaction between the KrF and KrCl excimer photons, respectively, and vibrationally hot ground state NS. LIF excitation scans on the NS X 2Π1/2,3/2 → B 2Π1/2,3/2 system confirm the production of rotationally and vibrationally excited NS(X) up to v″=4. A mechanism, based on the experimental data (i.e., spectral composition, laser fluence studies, excited state time histories), calculated heats of formation, and Gaussian molecular orbital calculations, is proposed to account for the observed emissions. For photolysis at 248 nm it is hypothesized that a two photon absorption promotes the ground singlet state of S4N4 to an upper repulsive singlet state, which rapidly dissociates (τ≪30 ns), producing an acyclic S3N3 fragment and vibrationally excited monomeric NS(X). The photofragments can interact further with the excimer radiation to produce NS(B) and NS(H), respectively. A similar mechanism is proposed to account for the presence of the NS(B) and NS(C) excited states for the 222 nm photolysis.

Ab initio studies of hydrogen bonding in the complexes of HNC, HCP, FCN, ClCN and BrCN with HF, HCl and HBr

Large basis set gaussian orbital SCF-MO calculations are presented for the hydrogen-bonded complexes formed between HNC, HCP, FCN, ClCN and BrCN with HF, HCl and HBr. Calculated equilibrium geometries, hydrogen bond energies and various one-electron properties are given to supplement available experimental data. Changes in electron distribution on complex formation are discussed in terms of Mulliken population analysis indices.

Ab initio study of the hydrogen-bonded complexes NH 3 ⋯ HCN, PH 3 ⋯ HCN, AsH 3 ⋯ HCN, H 2O ⋯ HCN, H 2S ⋯ HCN and H 2Se ⋯ HCN

Large basis set gaussian orbital SCF-MO calculations are presented for NH 3 ⋯ HCN, PH 3 ⋯ HCN, AsH 3 ⋯ HCN, H 2O ⋯ HCN, H 2S ⋯ HCN and H 2Se ⋯ HCN. Calculated equilibrium geometries, hydrogen bond energies and one-electron properties are given to supplement available experimental data. Changes in electron distribution on complex formation are discussed in terms of Mulliken population analysis indices.

An ab initio SCF-MO study of the hydrogen-bonded complexes formed between cyanoacetylene HCCCN and HF/HCl/HBr

Large basis set gaussian orbital SCF-MO calculations are presented for the complexes formed between HCCN and HF/HCl/HBr. Calculated equilibrium geometries, energies and one-electron properties are given in order to supplement the available experimental data. Changes in electron density on complex formation are discussed in terms of Mulliken population analysis indices.

Ab initio study of the hydrogen-bonded complexes NH3⋯HBr, PH3⋯HBr, AsH3⋯HF, AsH3⋯HCl and AsH3⋯HBr

Large basis set Gaussian orbital SCF-MO calculations are present for the title molecules. Calculated equilibrium geometries, hydrogen bond energies and one-electron properties are given to supplement available experimental data. Changes in electron distribution on complex formation are discussed in terms of Mulliken population analysis indices.

Ab initio study of the hydrogen-bonded complexes NH 3⋯HBr, PH 3⋯HBr, Ash 3⋯HF, AsH 3⋯HCI and Ash 3⋯HBr

Large basis set Gaussian orbital SCF-MO calculations are present for the title molecules. Calculated equilibrium geometries, hydrogen bond energies and one-electron properties are given to supplement available experimental data. Changes in electron distribution on complex formation are discussed in terms of Mulliken population analysis indices.

ChemInform Abstract: AB INITIO STUDY OF THE HYDROGEN‐BONDED COMPLEXES H2X...HY (X = O, S, SE: Y = F, CL, BR)

Abstract Large basis set Gaussian orbital SCF-MO calculations are presented for the title molecules. Calculated equilibrium geometries, hydrogen bond dissociation energies and one-electron properties are presented to supplement available experimental data. Changes in electron distribution on complex formation are discussed in terms of Mulliken population analysis indices.

Ab initio study of the hydrogen-bonded complexes formed between N 2/P 2 and HF/HCl/HBr

Large basis set Gaussian orbital SCF-MO calculations are presented for the title molecules. Calculated equilibrium geometries, hydrogen bond energies and one-electron properties are given to supplement available experimental data. Changes in electron distribution on complex formation are discussed in terms of Mulliken population analysis indices.

Ab initio study of the hydrogen-bonded complexes H 2X⋯HY (X = O, S, Se: Y = F, Cl, Br)

Large basis set Gaussian orbital SCF-MO calculations are presented for the title molecules. Calculated equilibrium geometries, hydrogen bond dissociation energies and one-electron properties are presented to supplement available experimental data. Changes in electron distribution on complex formation are discussed in terms of Mulliken population analysis indices.

Hydrogen bonding in ethene ⋯ HCN and ethyne ⋯ HCN: An ab initio SCF-MO study

Large-scale gaussian orbital SCF-MO calculations are presented for ethene—HCN and ethyne—HCN. Calculated equilibrium geometries, hydrogen-bond dissociation energies and one-electron properties are given to supplement available experimental data. Changes of electron distribution on complex formation are discussed in terms of Mulliken population analysis indices.

Ab initio study of the hydrogen bonded complexes CH 3⋯HF and CH 3F⋯HF

Large-scale gaussian orbital SCF-MO calculations are presented for the title molecules. Calculated equilibrium geometries, hydrogen-bond dissociation energies and one-electron properties are given to supplement available experimental data. Changes of electron distribution on complex formation are discussed in terms of Mulliken population analysis indices.

Virial theorem in the density-functional formalism: Forces inH2

The virial expression valid in density-functional theory contains an integral over the gradient of the effective exchange-correlation potential. The significance of this term in correcting the noninteracting kinetic and electrostatic energies is discussed in this work. From the gradient integral in the local density approximation an expression is derived for the kinetic-energy part of the exchange-correlation energy density, and its connection with the derivation of von Barth and Williams is discussed. To illustrate the application of these developments to the molecular case results are presented from Gaussian-orbital cluster calculations for H/sub 2/. In this study the forces in the dimer are calculated using the Hellmann-Feynman and virial theorems, and results are compared with the force obtained by direct interpolation from the binding-energy curve. The usefulness of the various methods for calculating the force is discussed.

Hydrogen bonding in oxirane…HF; an ab initio SCF-MO study

Large basis set gaussian orbital SCF-MO calculations including geometry optimization are reported for the hydrogen bonded complex oxirane…HF. Re(O…H) is predicted to be 181.2 pm, De(O…H) is predicted to be 34.6 kJ mol−1 and the change in dipole moment on complex formation is predicted to be 3.045 × 10−30 C m. The likely accuracy of the predictions is inferred from the agreement between previous theoretical results on HCN...HF with experimental microwave studies. STO/4-31G results are also presented and the importance of counterpoise corrections in such smaller basis set calculations is discussed.

Electronic structure and π electron magnetic susceptibility anisotropy in first and second row substituted heterobenzenes

The results of ab initio floating gaussian orbital calculations on C 5H 5X (X = CH, N, O +, SiH, P and S +) are used to obtain the dominant π-electron contribution to the molar magnetic susceptibility anisotropy for each compound studied. By choosing benzene to be the prototypical aromatic system and comparing relative anisotropies, the following ordering is produced (X in C 5H 5X): CH > S + > N ≈ P > SiH ≈ O +.

A Floating Gaussian Orbital calculation on argon hydrochloride (Ar � HCl)

The electronic structure, properties and binding of the argon hydrochloride (Ar-HCl) complex are discussed in connexion with simpleab initio Floating Gaussian Orbital calculations on the system.

A new, simple ab initio pseudopotential for use in floating spherical Gaussian orbital calculations. 2. Some results for hydrocarbons

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA new, simple ab initio pseudopotential for use in floating spherical Gaussian orbital calculations. 2. Some results for hydrocarbonsS. Topiol, A. A. Frost, J. W. Moskowitz, and M. A. RatnerCite this: J. Am. Chem. Soc. 1977, 99, 13, 4276–4278Publication Date (Print):June 1, 1977Publication History Published online1 May 2002Published inissue 1 June 1977https://doi.org/10.1021/ja00455a011RIGHTS & PERMISSIONSArticle Views40Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (382 KB) Get e-Alerts Get e-Alerts

Pseudopotential calculations using the FSGO method: Applications to first-row hydrides

Various pseudopotential schemes are examined in floating spherical Gaussian orbital (FSGO) calculations on the first row hydrides to help determine which pseudopotential scheme, if any, would be most useful in the FSGO method.

Use of pseudopotentials within the floating spherical Gaussian orbital method: Calculations on methane

The utility of nonempirical pseudopotentials in floating spherical Gaussian orbital (FSGO) calculations is examined. Calculations on the methane molecule with various popular pseudopotentials reveal that the best pseudopotentials may not be the most compatible with FSGO’s, but that in all cases, proper treatment of the angular momentum dependence is important.