Ab Initio Simulation of the IR Spectrum of Hydrated Kaolinite

The hydration of the basal surfaces of kaolinite is studied by theoretical methods. The cluster method was used to simulate the positions of atoms. The positions of the atoms of the basal surfaces of dry and hydrated minerals are optimized by minimizing the total energy in the Hartree–Fock approximation. The adsorption energies of water molecules were calculated taking into account the fourth-order correlation corrections of Møller–Plesset perturbation theory. The formation of the IR spectrum of kaolinite in the range of wave numbers 2500–4500 cm−1 is studied. The experimentally observed effect of the change in relative intensity and position of the band with a change in the moisture content of the sample is interpreted.

Spectroscopic study of magnesium dinitrogen and sodium dinitrogen cation

ABSTRACT Despite its likely importance in astrochemistry, pure rotational spectra are not observable for gas-phase N2 since this molecule has no permanent dipole moment. Complexation of monomeric N2 with a cationic metal (MN2+) may be kinetically and thermodynamically favourable, and the detection of such MN2+ molecules could be useful tracers of N2 in order to probe its abundance and kinetics. Highly accurate quartic force field methods have been applied here to compute rotational and vibrational spectroscopic properties of the NaN2+ and MgN2+ molecules via a coupled cluster-based composite approach with additional corrections for post-CCSD(T) electron correlation and relativistic effects. The relative energies of various isomers have also been computed and show that both NaN2+ and MgN2+ have linear ground electronic states. At the highest level of theory, rotational constants (B0) of 4086.9 and 4106.0 MHz are predicted for NaN2+ and MgN2+, respectively, with dipole moments of 6.92 and 4.34 D, respectively, making them rotationally observable even at low concentrations. Post-CCSD(T) electron correlation corrections lower the N–N stretching frequency while relativistic corrections have a much smaller effect putting the fundamental frequencies at 2333.7 and 2313.6 cm−1, respective of NaN2+ and MgN2+ slightly above that in N2H+. Additive corrections do not significantly change the other two vibrational modes. An anharmonic, zero-point corrected N2 dissociation energy of 7.3 and 7.0 kcal mol−1 is, respectively, reported for NaN2+ and MgN2+ suggesting possible formation of these molecules in protoplanetary discs or planetary nebulae that are metal- and nitrogen-rich.

On plasmon contribution to the hot A0 condensate

In SU(2) gluodynamics, the Debye gluon contribution WD(A0) to the effective action of the temporal gauge field component (we consider A0 = const) in the background Rξext is calculated at high temperaturegauge. It is shown that at A0 ≠ 0 the standard definition k0 = 0 , |k| → 0 corresponds to long distance correlations for the longitudinal in internal space gluons. The transversal gluons become screened by the A0 background field. Therefore, they give zero contributions and have to be excluded from the correlation corrections. The total effective action accounting for the one-loop, two-loop, and correct WD(A0) satisfies Nielsen’s identity that proves gauge invariance of the A0 condensation phenomenon.