Jiří Fišer

An ab initio study of the CO–N2 complex

Abstract The interaction energy and van der Waals intermolecule bond length of several structures of the CO–N2 complex are calculated by the supermolecule CCSD(T) and MP4 methods using aug-cc-pVXZ (X=D,T,Q) basis sets extended by a set of midbond functions centered in the middle of the vdW bond. The most stable structures are found to be two distorted T-shaped configurations with the N atom pointing towards the C–O bond. This conclusion is compatible with the results of high-resolution infrared, microwave and millimeter studies.

Propagation of gravity waves and spread F in the low-latitude ionosphere over Tucumán, Argentina, by continuous Doppler sounding: First results

Results of systematic analysis of propagation directions and horizontal velocities of gravity waves (GWs) and spread F structures in low-latitude ionosphere (magnetic inclination ~27°) in Tucuman region, Argentina, are presented. Measurements were carried out by multipoint continuous Doppler system during 1 year from December 2012 to November 2013. It was found that meridian propagation of GWs dominated and that southward propagation prevailed in the local summer. Oblique spread structures observed in Doppler shift spectrograms and associated with spread F propagated roughly eastward at velocities from ~70 to ~180 m/s and were observed at night from ~ September to ~ March. The velocities were computed for 182 events and the azimuths for 64 events. Continuous Doppler sounding makes it possible to analyze more events compared to optical observations often used for propagation studies since the measurements do not depend on weather.

Combining rule for interaction energies of the (CO)2, (N2)2 and CO-N2 complexes

The relationship between interaction energies of the most stable structures of the (CO)2, (N2)2 and CO-N2 complexes is investigated using the supermolecule CCSD(T) and MP4 methods and aug-cc-pVXZ (X = D,T,Q) basis sets extended by a set of midbond functions centred in the middle of the intermolecular bond. A simple combining rule for interaction energies of this triad of clusters is proposed.

On the behavior of the low-lying 2Σ+ electronic states of NO

Abstract The electric-field gradients at both nuclei and the electric-dipole moments for low-lying 2 Σ + states of NO are calculated using the internally contracted multireference configuration interaction method. The changes in character of the wavefunctions with internuclear separation R are used to interpret the intricate pattern of the R-dependences of the physical quantities. The estimated magnitudes of the 14N nuclear quadrupole coupling constant and the electric-dipole moment at the N=0 and v=3 rovibrational level of the A 2 Σ + electronic state, 6.615 MHz and 0.950 D, respectively, are in good agreement with experimental data.

Nonlinear acoustic waves in the viscous thermosphere and ionosphere above earthquake

The nonlinear behavior of acoustic waves and their dissipation in the upper atmosphere is studied on the example of infrasound waves generated by vertical motion of the ground surface during the Mw 8.3 earthquake that occurred about 46 km from Illapel, Chile on September 16, 2015. To conserve energy, the amplitude of infrasound waves initially increased as the waves propagated upwards to the rarefied air. When the velocities of air particles became comparable with the local sound speed, the nonlinear effects started to play an important role. Consequently, the shape of waveform changed significantly with increasing height, and the original wave packet transformed to the “N-shaped” pulse resembling a shock wave. A unique observation by the continuous Doppler sounder at the altitude of about 195 km is in a good agreement with full wave numerical simulation that uses as an input the measured vertical motion of the ground surface.

Quasiclassical trajectories study on the two-dimensional model of the dissociative chemisorption of H2 on a lithium cluster surface

A two-dimensional H 2 Li 8 potential surface of “diatomics-in-molecules” quality is constructed and used in a quasiclassical trajectory model study of dissociative adsorption of H 2 on the cluster surface. The effect of the translational and vibrational energy of H 2 on the outcome of the collision with the surface is discussed.

Spin-adapted wave functions of the serber type and time reversal

A procedure is proposed for generating Serber-type spin eigenfunctions withMs = 0. The procedure uses the time-reversal invariance of these functions to increase the efficiency and to reduce the storage requirements. Simplifications in calculating the matrix elements of an observable operator which follow from the use of the time-reversal symmetry are briefly discussed.

Model study of the relaxation accompanying adsorption of atomic hydrogen on the Li(100) cluster surface

Relaxation effects in the (4, 1, 4) and (5, 4) Li9 clusters induced by interaction with H are studied using the diatomics-in-molecules method. Total electronic energies for the clusters are determined as functions of the Li-Li bond lengths, both in the absence and in the presence of hydrogen adsorbed in a position of C4v symmetry. Two models of cluster relaxation are considered, differing in which part of the cluster is allowed to relax. The calculations reveal that hydrogen adsorbed on the (100) cluster surface causes quite a significant contraction of the metal atoms. The effect of the cluster relaxation on the nonadiabatic coupling between the lowest two Born-Oppenheimer states of the hydrogen-cluster system is discussed.

Comment on “The diatomic dication CuZn2+ in the gas phase” [J. Chem. Phys. 135, 034306 (2011)]

In this Comment, the density functional theory (DFT) calculations carried out by Diez et al. [J. Chem. Phys. 135, 034306 (2011)] are revised within the framework of the coupled-cluster single double triple method. These more sophisticated calculations allow us to show that the (2)Σ(+) electronic ground state of CuZn(2+), characterized as the metastable ground state by DFT calculations, is a repulsive state instead. The (2)Δ and (2)Π metastable states of CuZn(2+), on the other hand, should be responsible for the formation mechanism of the dication through the near-resonant electron transfer CuZn(+) + Ar(+) → CuZn(2+) + Ar reaction.

Model study of the nonadiabatic effects in the interaction of atomic hydrogen with lithium metal clusters

Study is made of the effects of adsorption site position on mutual arrangement and nonadiabatic coupling between the lowest two singlet potential energy surfaces of the Li9(4, 1, 4)-H chemisorption system. Special attention is paid to a normal approach of H atom to Li9 cluster. The necessary energy and coupling data are obtained by use of the method of the diatomics-in-molecules. The changes with the alteration of the adsorption site position of the degree of nonadiabatic behaviour of system is shown to be quite significant.