Ab initio quantum study of nonadiabatic S(1)-S(2) photodynamics of s-trans-butadiene.

The nonadiabatic photodynamics of s-trans-butadiene in its lowest singlet excited states is studied theoretically, using a fully quantal approach. The coupled 1Bu and 2Ag states are considered in the calculation, representing the lowest dipole-allowed electronic transition, and the dipole-forbidden state with substantial double-excitation character, respectively. Up to six nuclear degrees of freedom, including out-of-plane dihedral angles, are included. The calculation of the underlying potential energy surfaces relies on the CASPT2 method, where widely different CAS spaces have been compared. The ultrafast electronic population decay is confirmed, proceeding on a time scale of 30-40 fs. Pronounced out-of-plane distortions are obtained for the first time from fully quantal calculations. The complexity of the electronic absorption spectrum increases substantially upon including additional vibrational modes in the calculation. Further computations were performed to facilitate inclusion of the coupling to the ground state in subsequent work.

The predicted spectrum and singlet-triplet interaction of the hypermetallic molecule SrOSr.

In accordance with previous studies in our group on Be, Mg, and Ca hypermetallic oxides, we find that SrOSr has a linear X̃1Σ(g)+ ground electronic state and a very low lying first excited ã3Σ(u)+ triplet electronic state. No gas-phase spectrum of this molecule has been assigned yet, and to encourage and assist in its discovery we present a complete ab initio simulation, with absolute intensities, of the infrared absorption spectrum for both electronic states. The three-dimensional potential energy surfaces and the electric dipole moment surfaces of the X̃1Σ(g)+ and ã3Σ(u)+ electronic states are calculated using a multireference configuration interaction (MRCISD) approach in combination with internally contracted multireference perturbation theory (RS2C) based on complete active space self-consistent field (CASSCF) wave functions applying a Sadlej pVTZ basis set for both O and Sr and the Stuttgart relativistic small-core effective core potential for Sr. The infrared spectra are simulated using the MORBID program system. We also calculate vertical excitation energies and transition moments for several excited singlet and triplet electronic states in order to predict the positions and intensities of the most prominent singlet and triplet electronic absorption bands. Finally, for this heavy molecule, we calculate the singlet­triplet interaction matrix elements between close-lying vibronic levels of the X̃ and ã electronic states and find them to be very small.

The predicted spectrum of the hypermetallic molecule MgOMg.

The present study of MgOMg is a continuation of our theoretical work on Group 2 M(2)O hypermetallic oxides. Previous ab initio calculations have shown that MgOMg has a linear (1)Σ(g)+ ground electronic state and a very low lying first excited triplet electronic state that is also linear; the triplet state has (3)Σ(u)+ symmetry. No gas phase spectrum of this molecule has been assigned, and here we simulate the infrared absorption spectrum for both states. We calculate the three-dimensional potential energy surface, and the electric dipole moment surfaces, of each of the two states using a multireference configuration interaction (MRCISD) approach based on full-valence complete active space self-consistent field (FV-CASSCF) wavefunctions with a cc-pCVQZ basis set. A variational MORBID calculation using our potential energy and dipole moment surfaces is performed to determine rovibrational term values and to simulate the infrared absorption spectrum of the two states. We also calculate the dipole polarizability of both states at their equilibrium geometry in order to assist in the interpretation of future beam deflection experiments. Finally, in order to assist in the analysis of the electronic spectrum, we calculate the vertical excitation energies, and electric dipole transition matrix elements, for six excited singlet states and five excited triplet states using the state-average full valence CASSCF-MRCISD/aug-cc-pCVQZ procedure.

A detailed analysis of the spin-crossover reaction of H2S binding to heme and the six-coordinated FeP(Im)-HS- porphyrin complex.

The potential energy surfaces of the H2S binding to iron-porphyrin (FeP) with the imidazole (Im) ligand via intersystem crossings are investigated by using density functional theory. The minimum energy intersystem crossing point (MEISCP) between the quintet and triplet states (MEISCPTQ) for the Fe(II)P(Im)-H2S complex is located at a Fe-S distance of 3.39 Šwith only 1.1 kcal/mol above the quintet state minimum. The second spin-crossover point, where a change from the triplet to the singlet state occurs, comes at a much shorter Fe-S distance of 2.79 Å, and the MEISCPST is located at 3.7 kcal/mol above the triplet state minimum. The nature of the chemical bonding along the Fe-S reaction coordinate from the ground state singlet to the quintet state along the path to the separated species is analyzed. An inspection of the vibrational modes reveals that the largest contribution to the triplet-quintet transition around the quintet and triplet state minimum comes from the symmetric shrinking of the pyrrole units of the porphyrin ring, indicating that the related reaction coordinate plays a main role in the intersystem crossing. The fully optimized structures of the Fe(II)P(Im)-HS- complex corresponding to three different spin multiplicities (M = 1, 3, 5) are characterized by a bent Fe-H-S conformation. The binding of the hydrosulfide anion to Fe(II)P(Im) in the quintet state induces a 0.2 Šdisplacement of the Fe atom out of the nitrogen porphyrin (Npyr) plane. The fully optimized structure of the ground state of Fe(II)P(Im)-HS- agrees well with experimental data for the corresponding heme models.

Modeling the hydrogen sulfide binding to heme.

The binding of hydrogen sulfide to a model heme compound is investigated by coupled-cluster singles-doubles augmented by a perturbative triple excitations, CCSD(T), and density functional theory, DFT. The minimum energy path for the H2S addition to an isolated heme center of the heme protein is evaluated by adopting as a model the heme compound FeP(Im) (P = porphyrin; Im = imidazole). The FeP(Im)-H2S aduct is bound by 13.7 kcal/mol at the CCSD(T) level of theory. Relaxed potential energy curves for the lowest lying spin states of the H2S to FeP(Im) binding using DFT reveal that the binding process is associated with a "double spin-crossover" reaction with the existence of long-distance van der Waals minima only 5-7 kcal/mol above the FeP(Im)-H2S ground state. The fact that the energy of the singlet ground state of FeP(Im)-H2S is so close in energy to the dissociation products FeP(Im) + H2S points towards the reversibility of the H2S adsorption/desorption process in biochemical reactions.

Theoretical study of nitrodibenzofurans: A possible relationship between molecular properties and mutagenic activity.

In this study we present a theoretical investigation of the molecular properties of nitrodibenzofurans (NDFs) and dinitrodibenzofurans (DNDFs) and their relation to mutagenic activity. Equilibrium geometries, relative energies, vertical ionization potentials (IP), vertical electron activities (EA), electronic dipole polarizabilities, and dipole moments of all NDFs and three DNDFs calculated by Density Functional Theory (DFT) methods are reported. The Ziegler/Rauk Energy Decomposition Analysis (EDA) is employed for a direct estimate of the variations of the orbital interaction and steric repulsion terms corresponding to the nitro group and the oxygen of the central ring of NDFs. The results indicate differences among NDF isomers for the cleavage of the related bonds and steric effects in the active site. The results show a good linear relationship between polarizability (<α>), anisotropy of polarizability (Δα), the summation of IR intensities (ΣIIR) and the summation of Raman activities (ΣARaman) over all 3N-6 vibrational modes and experimental mutagenic activities of NDF isomers in Salmonella typhimurium TA98 strain. The polarizability changes with respect to the νsNO+CN vibrational mode are in correlation with the mutagenic activities of NDFs and suggest that intermolecular interactions are favoured along this coordinate.

[Urinary tract infection in patients with calculi]. / L'infection urinaire chez les lithiasiques.

The authors review a series of 2,475 cases of patients operated for renal calculi and select 843 files in which the bacteriological study was performed. E. coli is the most common organism (29.8%) compared with Proteus which infects 21% of patients. 71.5% of the patients were infected. Bilateral calculi are the most heavily infected. Kidneys containing calculi which were subjected to a complex operation involving the parenchyma (nephrotomies) were the most difficult to disinfect, even in the absence of recurrence. Conversely, in the absence of recurrence, simple operations (pyelotomy, partial nephrectomy) provide disinfection in the majority of cases. In the authors' series, E. coli remains the organism most frequently encountered, even in cases of recurrence. Proteus and Pyocyanicus are the most difficult organisms to eradicate.

Ab Initio Study of the Electronic Spectrum of B2H2

The present paper represents the first part of an extensive theoretical study on the electronic spectrum of B2H2. The results of ab initio calculations of the vertical spectrum and the trans- and cis-bending potential curves for the low-lying triplet and singlet electronic states are reported. Special attention is paid to the study of the interaction between valence- and Rydberg-type electronic species. Copyright 1997Academic Press

Ab Initio Study of the Electronic Spectrum of B2H2

The results of ab initio calculations of the potential curves for the torsional motion, symmetric H-B stretching, and B-B stretching in low-lying valence- and Rydberg-character triplet and singlet electronic states of B2H2 are reported. Particularly, the dissociation process B2H2 --> BH + BH out of various electronic states of B2H2 is studied. The nature of binding in B2H2 is discussed in terms of the composition of the electronic wavefunctions. Copyright 1997Academic Press

[Psychomotor development in children born with anoxia--perinatal risk factors]. / Psihomotorni razvoj dece rodene u anoksiji--perinatalni faktori rizika.

In 1989 a control of psychomotor development was conducted in 318 children born with the Apgar score of 7 and less. The children controlled were of the age of 3 months to 6.5 years old. Clinical examination and the testing of children of up to the age of one year according to Brunet Lezin have shown a decrease in the number of points of nine children (4.05%). The finding points to a deviation in psychomotor development of a mild degree. Out of 80 preschool children, 8% of them had clinically evident signs of a possible cortical lesion, which were discreet and regarded the visuomotor, in other words visuoconstructive functions.

[The effect of pH values and the method of delivery on intrapartum injuries in the neonate]. / Uticaj pH vrednosti i nacina zavrsavanja porodaja na intrapartalne povrede novorodenceta.

pH values of the blood taken intrapartally from the presenting part of fetus was analysed in 255 deliveries. The analysis comprised pH values of newborns born by Cesarean section in which pH values were determined from the blood of the umbilical cord, immediately after birth. The authors also analysed pH values in newborns born by vacuum extraction as well as in normal vaginal deliveries, and pH values were determined from the blood of the umbilical cord, immediately after birth. A part of this paper dealt with the influence of pH values on glycolysis of human fetal erythrocytes (in vitro). Decrease in pH values below 7.25 led to the slowness of the glycolysis process which was two times faster when pH values were over 7.30. The influence of pH values on intrapartal injuries of newborns was investigated in the application of vacuum extraction. These injuries were more frequent in newborns which are in acidosis, i.e. with lower values of pH blood. The authors concluded that vacuum extraction itself did not lead to injuries, but only augmented sensibility, i.e. decreased resistance of the tissue which was in acidosis were in question. They believed that vacuum extraction was a good method when applied on time in indicated cases.