Excitation energies, electron affinities and ionization potentials of the transition metals V, Cr and Mn

 Configuration interaction calculations were carried out for neutral ground and excited states and positively and negatively ionized states of the V, Cr and Mn atoms. Energy convergence with respect to systematic expansion of both the one-electron and configuration bases was investigated for valence correlation. Contributions from core electrons to the differential correlation energies and relativistic effects were evaluated separately. Assuming additivity of these contributions, excitation energies, electron affinities and ionization potentials of the atoms were obtained. All calculated values were in excellent agreement with the observed values within a deviation of 0.056 eV except for the electron affinity of the V atom, which had a calculated value 0.110 eV larger than the experimental value. Received: 9 August 2000 / Accepted: 26 October 2000 / Published online: 3 April 2001     

Atomic ionization potentials and electron affinities with relativistic and mass corrections

Relativistic corrections to ionization potentials (IPs) and electron affinities (EAs) of atoms with an atomic number Z≤54 are examined based on the first-order perturbation theory with an approximate Schr?dinger form of the Dirac-Coulomb-Breit Hamiltonian. Using a Hartree-Fock (HF) wave function from the numerical HF method as the unperturbed function, both the LS-non-splitting and fine-structure corrections are evaluated together with the normal and specific mass corrections. The LS-non-splitting corrections are found to be important for IPs and EAs of transition metal atoms. The fine-structure corrections are generally larger in magnitude than the LS-non-splitting corrections for the atoms of groups 13–18 with Z≥31, and can never be neglected. Comparison of the IPs and EAs presented here and experimental IPs and EAs gives an estimation of the electron correlation correction for these properties. For some light atoms, the estimated values agree with the results directly obtained from correlated calculations. Received: 28 January 1997 / Accepted: 4 March 1997     

Complete basis set ab initio computational study of ionization potential, electron affinity and the C-F bond dissociation energy for perfluorinated methane derivatives

A computational study of perfluorinated methane derivatives was performed with complete basis set ab initio methods. The total energies for their neutral, cation, and anionic states were computed. From these values, the energy gaps between different electronic states, ionization potentials, electron affinities, and C-F bond dissociation energies were calculated. The computed values are compared with experimental data and the reliability of complete basis set ab initio methods is discussed. New values for C-F bond dissociation energies are suggested. Received: 12 January 1998 / Accepted: 2 April 1998 / Published online: 29 July 1998     

Cations of halogenated methanes: adiabatic ionization energies, potential energy surfaces, and ion fragment appearance energies

The DFT-B3LYP and G3X model chemistry were used to predict the cation structures and energetics of fluorinated, chlorinated, and brominated methanes. Ion–complex structures between methylene cations and HX (X = F, Cl, Br) were found for all H-containing cations, and [CHF–FH]⁺, [CF₂–FH]⁺, [CCl₂–ClH]⁺, and [CCl₂–FH]⁺ structures are more stable than their normal tetravalent structures. Several cations should also be better described as ion–complex structures between methyl cations and halogen atoms, e.g., [CF₃–Br]⁺. Transition states connecting normal and ion–complex structures were also located, and potential energy diagrams were constructed for decomposition of methane cations and to predict the fragmentation pathways. The G3X energies were used to predict the adiabatic ionization energies (IE_as) and ion fragment appearance energies (AEs) from methanes. Many of the experimental AEs correspond to the energies of transition states instead of the thermodynamic dissociation limits. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Reactions of Hf, Ta, and W with O2 and CO: Metal carbide and metal oxide cation bond energies

The reactions of Hf⁺, Ta⁺, and W⁺ with O₂ and CO are studied as a function of translational energy in a guided ion beam tandem mass spectrometer. All three reactions with O₂ form diatomic metal oxide cations in exothermic reactions that occur at the collision rate. In the CO systems, formation of both diatomic metal oxide and metal carbide cations is observed to be endothermic. The energy-dependent cross sections in the latter systems are interpreted to give 0 K bond energies (in eV) of D₀(HfC⁺) = 3.19 ± 0.03, D₀(TaC⁺) = 3.79 ± 0.04, D₀(WC⁺) = 4.76 ± 0.09, D₀(HfO⁺) = 6.91 ± 0.11, D₀(TaO⁺) = 7.10 ± 0.12, and D₀(WO⁺) = 6.77 ± 0.07. The present experimental values for TaO⁺ and WC⁺ agree well with literature thermochemistry, those for HfO⁺ and WO⁺ refine the available literature bond energies, and those for HfC⁺ and TaC⁺ are the first measurements available. The nature of the bonding in MO⁺ and MC⁺ is discussed and compared for these three metal ions and analyzed using theoretical calculations at a B3LYP/HW+/6-311+G(3df) level of theory. Bond energies for all MO⁺ and MC⁺ species are calculated using geometries calculated at this level and single point energies determined at B3LYP, CCSD, CCSD(T), QCISD, and QCISD(T) levels of theory with the same basis set. Reasonable agreement between the theoretical and experimental bond energies for the three metal oxide and three metal carbide cations is found. Potential energy surfaces for reaction of the metal cations with CO are also calculated at the B3LYP level of theory and reveal additional information about the reaction mechanisms.     

DFT calculations of the ionization potentials and electron affinities of serinamide

Adiabatic and vertical ionization potentials (IPs) and valence electron affinities (EAs) of serinamide in the gas phase have been determined using density functional theory (DFT) B3LYP, B3P86, and B3PW91 methods with the 6‐311++G** and 6‐311G** basis sets, respectively. IPs and EAs of serinamide in solution have been calculated with the B3LYP method using the 6‐311++G** and 6‐311G** basis sets. Eight possible conformers of serinamide and its charged states in the gas phase have been optimized employing the DFT B3LYP method with 6‐311++G** and 6‐311G** basis sets, respectively. All the adiabatic and vertical ionization potentials (AIPs and VIPs) of eight serinamide conformers in our work are positive values, whether in the gas phase or in solutions; the IPs in solutions are smaller than the results in the gas phase and decrease with increased dielectric constants in solutions. This finding indicates that the cationic states in solutions are more stable than those in the gas phase. All EAs of eight serinamide conformers are negative values in the gas phase, indicating that the anionic states are unstable with respect to electron autodetachment, both adiabatically and vertically. In contrast, all other adiabatic electron affinities (AEAs) are negative values in solutions except for 6S in water; 7S in chloroform, acetone, and water; and 8S in acetone and water, and increase with increasing of dielectric constants in solutions. All vertical electron affinities (VEAs) are negative values in solutions; however, no good rule has been found for these values in solutions. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Application of the independent electron pair approach to the calculation of excitation energies,ionization potentials,and electron affinities of first row atoms

Excitation energies, first ionization potentials and electron affinities of first row atoms are calculated with a spin-adapted independent electron pair approximation (IEPA) combined with the direct determination of pair natural orbitals (PNOs). To enable comparison with molecular calculations Gaussian basis sets are used which are small enough to be also applicable to molecules. IEPA results for the above mentioned properties are accurate to 0.1–0.3 eV which is almost one order of magnitude better than the corresponding SCF-results. The same accuracy can be expected for molecules in which a localization of the doubly and singly occupied orbitals is possible, for instance for small hydrides. This is supported by the results of calculations on carbon hydrides.     

Electron affinities of heavier phosphoryl and thiophosphoryl halides APX3 (A = O, S and X = Br, I)

We carried out computational studies of OPX₃ and SPX₃ (X = Br and I) molecules and their corresponding anions using density functional theory, Møller‐Plesset, and CCSD(T) methods with newly developed model core potentials (MCP). Reliabilities of the MCP were demonstrated by comparing experimental and calculated results. We computed the geometric structure, electron affinities, and electrostatic moments using systematic sequences of the dzp‐, tzp‐, and qzp‐quality basis sets. Both C_3v and C_s symmetries were assumed to ascertain that minima on the potential energy surface were found. Infrared and Raman frequencies were calculated and compared with available experimental data. Natural population analyses were performed and used to determine distribution of the extra electron in anions. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007     

Complete basis set, the MP2 ab initio, and hybrid density functional theory evaluation of ionization potential and electron affinity for PH, PH2, PHF, PF, and PF2

A systematic study was performed on the small molecular systems built from phosphor, hydrogen and fluorine with the target being to evaluate accurately their ionization potentials and electron affinities, as well as influence fluorine on the ionization potential of phosphor as a central atom. To determine the accuracy of hybrid density functional methods for computing those energies, ionization energies for hydrogen, fluorine and phosphor were calculated and compared with the experimental and CBSQ values. To demonstrate the accuracy of this method, both the ionization potential and the electron affinity for phosphorus and fluorine atoms were calculated and compared with the experimental data. For both PF and PF₂, an identical electron affinity of 0.72 eV and for PH and PHF 1.0 eV were suggested.     

Basis set limit electronic excitation energies, ionization potentials, and electron affinities for the 3d transition metal atoms: Coupled cluster and multireference methods

Recently developed correlation consistent basis sets for the first row transition metal elements Sc-Zn have been utilized to determine complete basis set (CBS) scalar relativistic electron affinities, ionization potentials, and 4s(2)3d(n-2)-4s(1)d(n-1) electronic excitation energies with single reference coupled cluster methods [CCSD(T), CCSDT, and CCSDTQ] and multireference configuration interaction with three reference spaces: 3d4s, 3d4s4p, and 3d4s4p3d'. The theoretical values calculated with the highest order coupled cluster techniques at the CBS limit, including extrapolations to full configuration interaction, are well within 1 kcal/mol of the corresponding experimental data. For the early transition metal elements (Sc-Mn) the internally contracted multireference averaged coupled pair functional method yielded excellent agreement with experiment; however, the atomic properties for the late transition metals (Mn-Zn) proved to be much more difficult to describe with this level of theory, even with the largest reference function of the present work.     

Structural influence of transition metal (Sc,Y, and Lu) atoms inside gold nanoparticles

We theoretically investigated the influences of dopant transition metal atoms on structures and stability of gold nanoparticles. The optimized structures of Au₃M and Au₃M in an Au₃₂ cage (M = Au, Sc, Y, and Lu) obtained using relativistic density functional theory, show different configurations. Substitutions of one Au atom in the Au₄ cluster by only one M atom cause the Au₃M clusters to form equilateral triangles where M atoms prefer the central position, which is different from the original rhombus structure of a pure Au₄ cluster. All Au₃M nanoparticles, however, assume stable tetrahedral configurations in the Au₃₂ cage. Analysis of electronic structures indicates that the equilateral triangle Au₃M nanoparticles have higher chemical stability, in other words, lower reactivity than Au₃M@Au₃₂, while interaction energies between M and Au atoms in the Au₃M are smaller than those in Au₃M@Au₃₂. Different amounts of charge transfer and orbital hybridizations between the Au and M cause the change of the chemical stability and interaction energies. Our results indicate the potential manipulation of gold nanoparticle reactivity by metal substitution.     

Application of multiconfigurational many-body perturbation theory to the calculation of ionization potentials,electron affinities and excitation energ

Multiconfigurational many-body perturbation theory is applied to the problem of calculating ionization potentials, electron affinities, and excitation energies. H₂O, C₂H₄, and H₂ are studied, with correlation corrections through third order and inclusive of certain higher-order terms. Results are compared with those by other many-body theoretical methods.     

Second-order Green's function calculations of the ionization potential of a (H2)7 chain embedded in a homogeneous electric field

Summary The vertical ionization potential and the related pole strength of a model alternant chain of 14 hydrogen atoms subject to a homogeneous electric field, parallel to the chain and of increasing intensity are calculated, in the framework of a 6–31G** basis set, at the second-order level of the many-body Green's function theory. Trends observed with orbital relaxation, pair removal and pair relaxation effects are interpreted in terms of deformations of the electron density.     

过渡金属(Ti,Zr,Mn,Cu,Mo,Cr,Co)离子掺杂的MCM-48的合成、表征与催化性能研究

合成了掺杂Ti、Zr、Mn、Cu、Mo、Cr、和Co过渡金属离子的中介孔分子筛MCM-48.通过TEM、孔分布测试、XRD、电子能谱、红外吸收及热失重分析对掺杂的MCM-48进行结构表征,并研究了其催化性能.结果表明,掺杂Ti、Cr、Zr的MCM-48具有优良的催化性能.     

DFT,CBS‐Q,W1BD and G4MP2 calculation of the proton and electron affinities,gas phase basicities and ionization energies of saturated and unsaturated carboxylic acids (C1–C4)

The proton affinities, gas phase basicities and ionization energies of formic acid, acetic acid, propanoic acid, 2‐propenoic acid, propiolic acid, butanoic acid, 2‐butenoic acid, 3‐botenoic acid, 2‐methyl‐propanoic acid and 2‐methyl‐2‐propenoic acid were calculated using the computational methods including B3LYP/6‐311++G(2df,p), CBS‐Q and G4MP2. Also, the considered properties were calculated using W1BD method only for formic and acetic acids. In addition, the electron affinities of the acids were calculated using B3LYP, CBS‐Q, G4MP2 and G2MP2 methods, separately. The calculations showed that the PA and gas phase basicity increase with the increase in the number of carbon atoms. The calculated Ionization energies of the unsaturated carboxylic acids are less than the corresponding saturated acids, which are in good agreement with the experimental results. © 2013 Wiley Periodicals, Inc.     

Ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and ionic radii of element Uus (Z = 117) and astatine

Multiconfiguration Dirac-Fock (MCDF) method was employed to calculate the first five ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and radii for the element Uus and its homologue At. Main valence correlation effects were taken into account. The Breit interaction and QED effects were also estimated. The uncertainties of calculated IPs, EAs, and IR for Uus and At were reduced through an extrapolation procedure. The good consistency with available experimental and other theoretical values demonstrates the validity of the present results. These theoretical data therefore can be used to predict some unknown physicochemical properties of element Uus, Astatine, and their compounds.     

N，N＇－二（2－羟基苄烯）－2－羟基苯甲基二胺及N，N＇－二（2－羟基苄基）－2－羟基苯甲基二胺与过渡金属配合物的合成和表征

在四氢呋喃中合成了Ｓｃｈｉｆｆ碱配体Ｎ，Ｎ＇－二（２－羟基苄烯）－２－羟基苯甲基二胺（ＳＢ）与二价过渡金属镍、铜、锌的三核或双核配合物；用钠汞齐还原ＳＢ得到了其氢化物Ｎ，Ｎ＇－二（２－羟基苄基）－２－羟基苯甲基二胺（ＨＳＢ），并在乙醇中合成了它与铜的双核配合物。对这些配合物进行了元素分析和热分析，并测定了电导、红外光谱和紫外光谱，确定了分子式，讨论了可能的配位结构。     

Computational studies of bond dissociation energies, ionization potentials, and heat of formation for NH and NH+. Are hybrid density functional theory methods as accurate as quadratic complete basis set and Gaussian-2 ab initio methods?

Ionization potentials, bond dissociation energies, and heat of formation for NH and NH⁺ molecular species as well as for their elements were computed with highly reliable quadratic complete basis set and Gaussian-2 ab initio methods. The results are compared with experimental results and the assurance of these ab initio approaches is assessed. The same studies were also performed with three hybrid density functional methods (B3LYP, B3P86, and B3PW91) in combination with variously sized basis sets. The computational results are discussed in light of density functional theory reliability for exploring the potential energy of small polar molecular systems. Received: 21 July 1997 / Accepted: 8 December 1997     

Structures,stabilities and adiabatic ionization and electron affinity energies of small sulfur clustersS 3-S 5

Summary The vertical and adiabatic ionization and electron affinity energies are calculated for the isomers ofS ₃,S ₄ andS ₅. For the existing isomers the structures of several ionic states were optimized using an RHF analytical gradient approach with a subsequent frequency analysis. The many-body effects were taken into account by Green function (for vertical energies) and CI (for vertical and adiabatic energies) techniques. The structural relaxation upon ionization or attachment of an electron is found to be of primary importance to account for the sequence of cationic states or the existence of a positive electron affinity.Dedicated to Professor W. Kutzelnigg on the occasion of his 60th birthday.     

Investigation of the oxygen affinity of manganese(II), cobalt(II) and nickel(II) complexes with some tetradentate Schiff bases

Oxygen absorption–desorption processes for square planar Mn(II), Co(II) and Mn(II) complexes of tetradentate Schiff base ligands in DMF and chloroform solvents were investigated. The tetradentate Schiff base ligands were obtained by condensation reaction of ethylenediamine with salcyldehyde, o-hydroxyacetophenone or acetylacetone in the molar ratio 1:2. The square planar complexes were prepared by the reaction of the Schiff base ligands with Mn(II) acetate, Co(II) nitrate and Ni(II) nitrate in dry ethanol under nitrogen atmosphere. The sorption processes were undertaken in the presence and absence of (pyridine) axial-base in 1:1 M ratio of (pyridine:metal(II) complexes). Complexes in DMF indicate significant oxygen affinity than in chloroform solvent. Cobalt(II) complexes showed significant sorption processes compared to Mn(II) and Ni(II) complexes. The presence of pyridine axial base clearly increases oxygen affinity.