Ab initio properties of MgAlk (Alk = Li, Na, K, Rb, Cs).

High level ab initio calculations are performed on the ground electronic state of diatomic molecules MgAlk (Alk = Li, Na, K, Rb, Cs). Potential energy curves and dipole moment functions are determined making use of the single-reference unrestricted and restricted coupled-cluster methods with large basis sets. Basic spectroscopic properties of the ground electronic states are derived from ro-vibrational bound state calculations.

International round-robin study on the Ames fluctuation test.

An international round-robin study on the Ames fluctuation test [ISO 11350, 2012], a microplate version of the classic plate-incorporation method for the detection of mutagenicity in water, wastewater and chemicals was performed by 18 laboratories from seven countries. Such a round-robin study is a precondition for both the finalization of the ISO standardization process and a possible regulatory implementation in water legislation. The laboratories tested four water samples (spiked/nonspiked) and two chemical mixtures with and without supplementation of a S9-mix. Validity criteria (acceptable spontaneous and positive control-induced mutation counts) were fulfilled by 92-100%, depending on the test conditions. A two-step method for statistical evaluation of the test results is proposed and assessed in terms of specificity and sensitivity. The data were first subjected to powerful analysis of variance (ANOVA) after an arcsine-square-root transformation to detect significant differences between the test samples and the negative control (NC). A threshold (TH) value based on a pooled NC was then calculated to exclude false positive test results. Statistically, positive effects observed by the William's test were considered negative, if the mean of all replicates of a sample did not exceed the calculated TH. By making use of this approach, the overall test sensitivity was 100%, and the test specificity ranged from 80 to 100%.

The heaviest group 2 Difluoride, RaF(2): geometry and ionization energy.

The heaviest group 2 difluoride, radium difluoride (RaF(2)), is studied for the first time. A basis set is employed for radium that combines an effective core potential with a large, flexible valence space. This basis set is tested by calculating the first and second ionization energies of Ra, where values in excellent agreement with experiment are obtained. MP2 ab initio calculations are employed to obtain the optimized equilibrium geometry and the harmonic vibrational frequencies for the ground-state neutral and some of the low-lying cationic states. In addition, the optimized geometry of the ground-state neutral is obtained at the CCSD(T) level. The trend in geometry of the group 2 difluorides is confirmed, with an angle FRaF bond angle of 118 degrees being calculated, together with a bond length of 2.30 A. It is concluded that involvement of the Ra 6p orbitals in the valence molecular orbitals of RaF(2) adequately explains its bent geometry. RCCSD(T) calculations are then employed to calculate ionization energies. The first adiabatic ionization energy, corresponding to the ionization (tilde)X(2)Sigma(u)(+) <-- (tilde)X(1)A(1), is calculated to be 10.67 +/- 0.05 eV. The ordering of the ionic states is discussed in the light of the present results. The polarizability of Ra was calculated to be 36.3 A(3), with that of Ra(2+) was calculated to be 1.97 A(3); the latter was employed in a simple ionic model, but this failed to calculate the ionization energy accurately.

Baia Mare accident--brief ecotoxicological report of Czech experts.

On 30 January 2000, following the breach in the tailing dam of the Aurul SA Baia Mare Co., a major spill of about 100,000 m(3) of cyanide and metal-rich liquid waste was released into the river system near Baia Mare in northwest Romania. The pollutants flowed via different tributaries into the Tizsa (Tisa) river and finally through the Danube river into the Black Sea. Along the way pollutants (especially cyanides) caused rapid death of aquatic organisms and animals living close to the poisoned rivers. Following request from the governments of Romania, Hungary, and the Federal Republic of Yugoslavia, United Nations sent international mission experts to the area of accident. The Czech team of four experts took very active part in this mission. Samples of surface water collected by this team 3 weeks after the accident showed high toxicity in the rivers on the Romanian territory. Due to this impact, water from the Szamos river and a large area of the Tisza river in Hungarian territory was still medially toxic. Improvement of this situation was detected only in downstream areas of the Tisza/Tisa river. The high toxicity of surface water from the locality of the Lapos river upstream of the accident indicated the possibility of toxic pollution from other sources in the area. Aquatic sediments were highly toxic only in the Aurul reservoir and its surrounding area. Rapid decline of their toxicity indicated more limited adverse impact of the "Aurul pollution" in comparison with surface water. From ecotoxicological results it is evident that there is an urgent need to start abatement activities in the Baia Mare area because the possibility of future accidents still exists (this hypothesis was proved by further accidents on 10.3.2000 and the beginning of May 2000).

Vibrational Dynamics of H5 + and Its Deuterated Isotopomers

The vibrational dynamics of the H5 + complex and its deuterated isotopomers H4 D+ , H3 D2 + , H2 D3 + , HD4 + , and D5 + are investigated using a model Hamiltonian which is based on the assumption that on the potential energy hypersurface the barriers for the internal rotation motions are infinitely high except for the practically free propeller-like motion. According to our previous studies on H5 + , the propeller-like rotation essentially does not interact with the remaining vibrations and is therefore neglected in the present calculations. Within the framework of the adiabatic approximation the resulting eight-dimensional vibrational problem is separated into two smaller subproblems which are solved numerically applying the same scheme as previously. The calculations are performed using a new extended potential energy function which also provides a reliable description of the interactions between the degenerate stretching motions and the remaining vibrations. As in our previous calculations, the high-frequency fundamentals obtained for H5 + are in good agreement with their experimental counterparts, whereas the reliability of the present results for the low-frequency motions is considerably improved as a result of the appropriate description of the relevant interactions. Predictions of the vibrational energies of the other deuterated isotopomers are made on the same accuracy level. The zero-point energies derived from the present calculations are believed to be accurate enough for a quantitative determination of the binding energies of the different isotopomers.

Symmetry Analysis of the Vibrational Dynamics of the H3 D2 + and H2 D3 + Complexes

A symmetry analysis of the H3 D2 + and H2 D3 + complexes in a model with one large amplitude motion, the propeller-like internal rotation, is presented. Symmetry coordinates and symmetry adapted polynomial expansions of the potential, dipole moment, and polarizability functions are derived within the framework of the extended molecular symmetry group G 3 (2, 2) using the projection operator and Molien function techniques.

Symmetry Analysis of Molecules Consisting of Two Coaxial Rotors Using the Extended Permutation-Inversion Groups

A general method for constructing permutation-inversion groups and their extensions to molecules containing two coaxial rotors is presented. Symmetry species of the dipole moment, tensor of polarizability, and total angular momentum operator are determined. General infrared and Raman selection rules, symmetry classifications of rotorsional, rotational, and torsional wavefunctions are derived. Theory is illustrated for the H3D+2 complex.