Hirotoshi Mori

Compact and efficient basis sets of s- and p-block elements for model core potential method

We propose compact and efficient valence-function sets for s- and p-block elements from Li to Rn to appropriately describe valence correlation in model core potential (MCP) calculations. The basis sets are generated by a combination of split MCP valence orbitals and correlating contracted Gaussian-type functions in a segmented form. We provide three types of basis sets. They are referred to as MCP-dzp, MCP-tzp, and MCP-qzp, since they have the quality comparable with all-electron correlation consistent basis sets, cc-pVDZ, cc-pVTZ, and cc-pVQZ, respectively, for lighter atoms. MCP calculations with the present basis sets give atomic correlation energies in good agreement with all-electron calculations. The present MCP basis sets systematically improve physical properties in atomic and molecular systems in a series of MCP-dzp, MCP-tzp, and MCP-qzp. Ionization potentials and electron affinities of halogen atoms as well as molecular spectroscopic constants calculated by the best MCP set are in good agreement with experimental values.

Experimental and Theoretical Approaches Toward Anion‐Responsive Tripod–Lanthanide Complexes: Mixed‐Donor Ligand Effects on Lanthanide Complexation and Luminescence Sensing Profiles

A new series of tripods were designed to form anion-responsive, luminescent lanthanide complexes. These tripods contain pyridine, thiazole, pyrazine, or quinoline chromophores combined with amide carbonyl oxygen and tertiary nitrogen atoms. Crystallographic and EXAFS studies of the 10-coordinated tripod-La(NO(3))(3) complexes revealed that each La(3+) cation was cooperatively coordinated by one tetradentate tripod and three bidentate NO(3)(-) anions in the crystal and in CH(3)CN. Quantum chemical calculations indicated that the aromatic nitrogen plays a significant role in lanthanide complexation. The experimentally determined stability constants of complexes of the tripod with La(NO(3))(3), Eu(NO(3))(3), and Tb(NO(3))(3) were in good agreement with the theoretically calculated interaction energies. Complexation of each tripod with lanthanide triflate gave a mixture of several lanthanide complex species. Interestingly, the addition of a coordinative NO(3)(-) or Cl(-) anion to the mixture significantly influenced the lanthanide complexation profiles. The particular combination of tripod and a luminescent Eu(3+) center gave anion-selective luminescence enhancements. Pyridine-containing tripods exhibited the highest NO(3)(-) anion-selective luminescence and thus permit naked-eye detection of the NO(3)(-) anion.

Revised model core potentials for first-row transition-metal atoms from Sc to Zn

We have developed new relativistic model core potentials (MCPs) for the first-row transition-metal atoms from Sc to Zn, in which 3s and 3p electrons are treated explicitly together with the 3d and 4s electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show reasonable performance in describing the electronic structures of atoms and molecules, bringing about accurate excitation energies for atoms and good molecular spectroscopic constants.

Structure and intermolecular hydrogen bond of jet-cooled p-aminophenol–(H2O)1 studied by electronic and IR-dip spectroscopy and density functional theory calculations

Abstract The structure and hydrogen bonding interaction in jet-cooled p -aminophenol–H 2 O 1:1 complex have been studied by measuring the fluorescence excitation, dispersed fluorescence, and IR-dip spectra. In the electronic spectrum we identified only one isomer, where the oxygen atom of water is bonded to the hydroxy proton of p -aminophenol. Four stable isomers are obtained by ab initio calculations at the MP2/6-31G(d) level, while density functional theory calculations provide four or three isomers depending on the basis sets. It has been shown that theoretical IR spectra with small basis sets are not in agreement with the experimental IR spectrum. The experimental IR spectrum has been well reproduced by the B3LYP/6-311+G(d,p) calculations, showing that diffuse functions are necessary to describe the intermolecular hydrogen bond in p -aminophenol–H 2 O. The vibronic levels in the S 1 state of p -aminophenol–H 2 O have been assigned with the aid of the dispersed fluorescence spectra. The formation of the intermolecular hydrogen bond substantially reduces the frequency of the amino inversion mode in the S 1 state due to nonlocal character of this mode.

Theoretical study on vibrational circular dichroism spectra of tris(acetylacetonato)metal(III) complexes: anharmonic effects and low-lying excited states.

The open-shell density functional theory calculations with M06 exchange-correlation functional and all-electron Douglas-Kroll second order scalar relativistic correction were performed to interpret the vibrational circular dichroism (VCD) spectra of four kinds of tris(acetylacetonato)metal(III), [M(III)(acac)(3)] (acac = acetylacetonato, M = Ru, Cr, Co, and Rh). It was deduced that the experimental spectra were well reproduced by the calculation with harmonic approximation in case of [Co(III)(acac)(3)] (d(6); S = 0), [Rh(III)(acac)(3)] (d(6); S = 0), and [Ru(III)(acac)(3)] (d(5); S = 1/2). In case of [Cr(III)(acac)(3)] (d(3); S = 3/2), anharmonic effects should be taken into account to predict the accurate vibrational frequencies of closely located modes. Time-dependent density functional theory calculations were performed to estimate the contribution of excited states in the VCD spectra. As a consequence, the presence of the low-lying excited states was predicted for [Ru(III)(acac)(3)] alone, which agreed with the experimental observation.

Model core potential and all-electron studies of molecules containing rare gas atoms.

Molecules HRgF (Rg = Ar, Kr, Xe, Rn) were studied at levels of theory that included electron correlation, taking relativistic effects into account either by using the recently developed parametrization of the extended model core potentials and basis sets or by using the Douglas-Kroll method with all-electron basis sets. Charge distributions were calculated according to Mulliken, Lowdin, and natural bond orbital methods of population analysis and the results of these methods were compared, confirming that bonding in these molecules corresponds to interaction between the fluoride anion and the RgH(+) moiety. In contrast to previously reported results, the present calculations show that the radon compound, HRnF, is more stable than compounds of the lighter congeners. Trends in the first ionization energies, bond lengths, energies of formation and decomposition, and harmonic vibrational frequencies were discussed and found to be consistent with the periodic trends of the atomic properties of the rare gas atoms.

Adaptive Application Composition in Quantum Chemistry

Component interfaces, as advanced by the Common Component Architecture (CCA), enable easy access to complex software packages for high-performance scientific computing. A recent focus has been incorporating support for computational quality of service (CQoS), or the automatic composition, substitution, and dynamic reconfiguration of component applications. Several leading quantum chemistry packages have achieved interoperability by adopting CCA components. Running these computations on diverse computing platforms requires selection among many algorithmic and hardware configuration parameters; typical educated guesses or trial and error can result in unexpectedly low performance. Motivated by the need for faster runtimes and increased productivity for chemists, we present a flexible CQoS approach for quantum chemistry that uses a generic CQoS database component to create a training database with timing results and metadata for a range of calculations. The database then interacts with a chemistry CQoS component and other infrastructure to facilitate adaptive application composition for new calculations.

Revised model core potentials of s-block elements.

We developed new model core potentials (MCPs) for s‐block elements from Na to Ra, in which the outer core (n − 1)s and (n − 1)p electrons are treated explicitly together with the ns electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show excellent performance in describing the electronic structures of atoms and molecules, bringing about accurate ionization potentials of atoms and very good spectroscopic constants of ionic and covalent molecules. The results obtained with the new MCPs are very close to the ones obtained using the all‐electron correlation consistent basis sets of Dunning.

Effects of intermolecular interaction on proton tunneling: Theoretical study on two-dimensional potential energy surfaces for 9-hydroxyphenalenone-CO2/H2O complexes

The effects of binding of CO2 or H2O with 9-hydroxyphenalenone (9HPO) on proton tunneling in the S0 state have been theoretically investigated. High-level ab initio calculations predict that CO2 is van der Waals-bonded to the C=O⋯OH moiety of 9HPO in the most stable structure. This planar structure is more stable than the nonplanar structure where CO2 is bonded above the aromatic rings of 9HPO. In the 9HPO–H2O complex, H2O is hydrogen-bonded to the carbonyl group in the most stable structure. Two-dimensional potential energy surfaces (PESs) for 9HPO–CO2 and 9HPO–H2O have been calculated with the reaction surface method, and the contour plots of PESs for the complexes are compared with those for the 9HPO monomer. The binding of CO2 with 9HPO induces slight asymmetry in the double-minimum potential well, whereas the asymmetry of the PES is very large for the binding of H2O. The transition state energy for 9HPO–CO2 drastically decreases to be about a half that of 9HPO, while that for 9HPO–H2O is only slightl...

Molecular orbital study for Na, Mg, and Al adsorption on the Si (111) surface

Abstract We investigated the interactions between the Si(111) surface and the Na, Mg, and Al atoms using cluster model calculations. Calculations were performed at levels of complete-active-space self-consistent-field (CASSCF) and multi-reference singly and doubly excited configuration interaction (MRSDCI) calculations using the model core potential method. Our calculations revealed that the most favorable sites of Na, Mg, and Al adsorption on Si(111) are on top (T1), bridge (B2), and 3-fold filled (T4) sites, respectively. The nature of chemical bonds between these metal atoms and the dangling bonds of the surface Si atoms are found to be essentially covalent.