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In search for future good adsorbents for CO2 capture, a nitrogen-rich triazole-type Metal–Organic Framework (MOF) is proposed based on the rational design and theoretical molecular simulations. The structure of the proposed MOF, named Zinc Triazolate based Framework (ZTF), is obtained by replacing the amine-organic linker of MAF-66 by a triazole, and its structural parameters are deduced. We used grand-canonical Monte Carlo (GCMC) simulations based on generic classical force fields to correctly predict the adsorption isotherms of CO2 and H2O. For water adsorption in MAF-66 and ZTF, simulations revealed that the strong hydrogen bonding interactions of water with the N atoms of triazole rings of the frameworks are the main driving forces for the high adsorption uptake of water. We also show that the proposed ZTF porous material exhibits exceptional high CO2 uptake capacity at low pressure, better than MAF-66. Moreover, the nature of the interactions between CO2 and the MAF-66 and ZTF surface cavities was examined at the microscopic level. Computations show that the interactions occur at two different sites, consisting of Lewis acid–Lewis base interactions and hydrogen bonding, together with obvious electrostatic interactions. In addition, we investigated the influence of the presence of H2O molecules on the CO2 adsorption on the ZTF MOF. GCMC simulations reveal that the addition of H2O molecules leads to an enhancement of the CO2 adsorption at very low pressures but a reduction of this CO2 adsorption at higher pressures. [ABSTRACT FROM AUTHOR]

Research designed to calculate the spectroscopic data of the electronic states of AlS in an energy domain up to 40000 cm-1 above the electronic ground state is presented. The theoretically spectroscopic constants fit in very well with those already obtained experimentally for five states.

Surface elasticity and nonlinear effects are reported in ZnO nanowires and characterized by ab initio calculations. Fully anisotropic elastic and stress coefficients related to (10[formula]0) surfaces are provided and used to construct a continuum model of nanowires based on the Gurtin-Murdoch surface elasticity theory, able to capture mechanical size effects. Nonlinear elasticity is observed through non-zero third order energy derivative terms with respect to axial strain in the direction of the nanowire. The associated material parameters are found to be themselves size-dependent. [ABSTRACT FROM AUTHOR]

Using highly correlated wave functions, the ground and the low lying excited states of the molecular NCO- and CNO- anions have been reinvestigated. The stability of the electronic ground state of the two isomers with respect to dissociation and to electron detachment has been checked along the isomerization pathway. The regions of stability of the excited electronic states have been analyzed and identified and it is shown that only the ground state is stable and the corresponding potential energy surface presents three equilibrium positions. The rovibronic spectroscopy of the X 1Σ+ state of both NCO- and CNO- isomers has been determined by a variational approach leading to remarkable agreement with experimental data. [ABSTRACT FROM AUTHOR]

For the van der Waals C2(X 1Σg+)–H2 molecular system, we generated a new ab initio potential energy surface (PES). We mapped this PES at the multireference internally contracted configuration-interaction method including the Davidson correction together with a large diffuse basis set. Then, we incorporated our PES into quantum scattering calculations at the close coupling and infinite order sudden approximation methods to cover collision energies ranging from 0.1 up to 4000 cm-1. After Boltzmann thermal averaging, rate coefficients for temperatures of up to 1000 K are deduced. Discrepancies between our new rates and those computed previously are noticed. This should induce deviations in astrophysical modeling. [ABSTRACT FROM AUTHOR]

Atomic pseudopotentials and highly correlated wave functions, including spin-orbit interactions, have been used to evaluate the electronic structure, stability, and spectroscopy of triatomic molecule MH2, with a metal M belonging to group IB (Cu, Ag, and Au). CuH2 and AuH2 have been recently observed by IR spectroscopy in solid hydrogen and bending anharmonic wave numbers have been assigned to these two systems. The AgH2 molecule has not been detected nor experimentally characterized, despite several theoretical works arguing on its stability. Our results confirm that the MH2 radicals have a metastable bent ground state separated from the dissociation into [M+H2] ground state by barriers which have been evaluated to 1.43, 0.78, and 0.80 eV, for Cu, Ag, and Au compounds, respectively. These barriers are calculated smaller than in previous determinations but still large enough to stabilize the MH2 systems. Spectroscopic data are calculated for these radicals. [ABSTRACT FROM AUTHOR]

Calculates the potential energy and spin-orbit functions for several electronic states of CS and CS[sup -]. Comparison with experimental data for CS; Electronic structure calculations performed with complete active space self-consistent field.

Investigates the use of potential energy functions for the electronic states of cesium sulfide (CS[sub 2][sup++]. Calculation of the photoelectron spectra in CS[sub 2][sup ++] ionization; Effects of Fermin resonances on symmetric stretching progressions; Occurrence of dissociation on the excited vibrational states in CS[sub 2][sup ++].

Radiative lifetimes of HBr+ and DBr+(2Π1/2, v=0, 1) have been determined using the monitor ion technique in a triple cell ICR spectrometer with Fourier transform detection. The experimental lifetimes corresponding to the vibrational transition v=1→0 are 10.2±1 ms and 56+12-11 ms for HBr+ and DBr+, respectively. The lifetimes calculated by a coupled electron pair approximation (CEPA) method similar to the method used previously for HF+ and HCl+ are 8.8 ms for HBr+ and 35.8 ms for DBr+, in rather good agreement with the experimental results. A comparison with previous experimental and theoretical results on hydrogen halides shows a shortening of the lifetime between the neutrals and the corresponding ions and a lengthening with isotopic substitution (H by D) as well as with substitution of F by Cl or by Br. The lifetimes corresponding to spin–orbit relaxation are very long 852+621-282 ms for HBr+ and 965+546-323 ms for DBr+. They can be considered as equal within the quite large experimental uncertainty on the contribution of collisional deactivation. [ABSTRACT FROM AUTHOR]

The conical intersection regions on the potential energy functions of the valence excited 1,3Σu-, 1,3Δu, 3Σu+, and 1,3Πg states of CO2 have been investigated by ab initio calculations. Using large scale multireference configuration interaction the ordering of the lowest valence excited states of CO2 has been calculated to be 3B2, 3A2, 1A2 followed by 1B2. All these states have bent equilibrium structures and lie energetically below their dissociation asymptotes. The near equilibrium parts of the potential energy functions have been mapped in three dimensions by multiconfiguration self-consistent field calculations. The 1,3B2 and 1,3A2 states differ in their equilibrium angles (118° and 127°, respectively), and have much longer equilibrium distances (around 1.26 Å) than the electronic ground state. Anomalously low values of ca. 800 cm-1 have been calculated for the wave number of the antisymmetric stretching vibrations of the 1A2, 3B2, and 1B2 states. The crossings between the bent valence excited states in the geometry region 90°≤αOCO≤150° and 1.1 Å≤RCO≤1.4 Å have been located. [ABSTRACT FROM AUTHOR]

The vacuum ultraviolet pulsed field ionization-photoelectron (PFI-PE) spectra for CS2 are measured in full energy range of 12.6-13.5 eV, revealing complex vibronic band structures for the CS2(super +)[A~(super 2)pi(sub u)] state. Three dimensional potential energy functions for CS2 (super +1)[A~(super 2)pi(sub u)] are also generated theoretically.