Cold reactive and non-reactive collisions of Li and Rb with C2−_2^-: implications for hybrid trap experiments

We present a theoretical investigation of cold reactive and non-reactive collisions of Li and Rb atoms with C$_{2}^{-}$. The potential energy surfaces for the singlet and triplet states of the Li--C$_{2}^{-}$ and Rb--C$_{2}^{-}$ systems have been obtained using the CASSCF/ic-MRCI+Q approach with extended basis sets. The potential energy surfaces are then used to investigate the associative detachment reaction and to calculate rotationally inelastic cross sections by means of the close-coupling method. The effect of the core correlation on the potential energy surfaces is discussed and we estimate the error on the collisional cross sections induced by freezing the $1s$ orbitals of the carbon atoms. The results are compared to those obtained for the Rb-OH$^{-}$ system and the applications for hybrid trap experiments are explored. Furthermore, we discuss the possibility to perform Doppler thermometry on the C$_{2}^{-}$ anion and investigate the collision process involving excited states. The implications for sympathetic cooling experiments are also discussed

Reactivity of hydrated hydroxide anion cluster OH(H2_{2}O)n−_{n}^{-} with H and Rb: an ab initio study

We present a theoretical investigation of the hydrated hydroxide anion clusters OH(H$_{2}$O)$_{n}^{-}$ and of the collisional complexes H-OH(H$_{2}$O)$_{n}^{-}$ and Rb-OH(H$_{2}$O)$_{n}^{-}$ (with n$=1-4$). The MP2 and CCSD(T) methods are used to calculate interaction energies, optimized geometries and vertical detachment energies. Part of the potential energy surfaces are explored with a focus on the autodetachment region. We point out the importance of diffuse functions to correctly describe the latter. We use our results to discuss the different water loss and electronic detachment channels which are the main reaction routes at room temperature. In particular, we have considered a direct and an indirect process for the electronic detachment, depending on whether water loss follows or precedes the detachment of the excess electron. We use our results to discuss the implication for astrochemistry and hybrid trap experiments in the context of cold chemistry

Interaction of CH3_3CN and CH3_3NC with He : potential energy surfaces and low-energy scattering

Several nitrogen-bearing molecules, such as methyl cyanide (or acetonitrile, CH$_3$CN) and methyl isocyanide (CH$_3$NC) of interest here, have been observed in various astrophysical environments. The accurate modeling of their abundance requires the calculation of rate coefficients for their collisional excitation with species such as He atoms or H$_2$ molecules at low temperatures. In this work we compute new three-dimensional potential energy surfaces for the CH$_3$NC-He and CH$_3$CN-He van der Waals complexes by means of the explicitly correlated coupled cluster approach with single, double and perturbative triple excitation CCSD(T)/F12a in conjunction with the aug-cc-pVTZ basis set. We find a global minimum with $D_e= 55.10$ and 58.61 cm$^{-1}$ for CH$_3$CN-He and CH$_3$NC-He, respectively, while the dissociation energy $D_0$ of the complexes are 18.64 and 18.65 cm$^{-1}$, respectively. Low energy scattering calculations of pure rotational (de-)excitation of CH$_3$CN and CH$_3$NC by collision with He atoms are carried out with the close-coupling method and the collisional cross sections of $ortho-$ and $para-$CH$_3$NC and CH$_3$CN are computed for kinetic energies up to 100 cm$^{-1}$. While the PESs for both complexes are qualitatively similar, that of CH$_3$NC-He is more anisotropic, leading to different propensity rules for rotational excitation. For CH$_3$NC-He, we find that |$\Delta j$| = 1 transitions are dominant at low kinetic energy and a propensity rule that favors odd $\Delta j$ transitions is observed, whereas for CH$_3$CN the dominant cross sections are associated to transitions with |$\Delta j$| = 2. We expect that the findings of this study will be beneficial for astrophysical investigations as well as laboratory experiments

Ab initio calculation of the 66 low lying electronic states of HeH+^+: adiabatic and diabatic representations

We present an ab initio study of the HeH$^+$ molecule. Using the quantum chemistry package MOLPRO and a large adapted basis set, we have calculated the adiabatic potential energy curves of the first 20 $^1 \Sigma^+$, 19 $^3\Sigma^+$, 12 $^1\Pi$, 9 $^3\Pi$, 4 $^1\Delta$ and 2 $^3\Delta$ electronic states of the ion in CASSCF and CI approaches. The results are compared with previous works. The radial and rotational non-adiabatic coupling matrix elements as well as the dipole moments are also calculated. The asymptotic behaviour of the potential energy curves and of the various couplings between the states is also studied. Using the radial couplings, the diabatic representation is defined and we present an example of our diabatization procedure on the $^1\Sigma^+$ states.Comment: v2. Minor text changes. 28 pages, 18 figures. accepted in J. Phys.

Knowledge management in construction

Na upravljanje z znanjem lahko gledamo kot na jasen in sistematičen način zajetja informacij in znanja nekega podjetja, njegovega razvoja, izdelkov, dela, trgovanja, strank in konkurence združenega na enem mestu, do katerega lahko dostopa ustrezno osebje, razpolaga z njim in ga koristno unovči. Gre za obširen in za vsako podjetje unikaten proces, ki predstavlja upravljanje z razumskimi sposobnostmi, zmožnostmi in spretnostmi zaposlenih v podjetju z namenom, da bi izboljšali učinkovitost podjetja in lažje obvladovali spremembe. Gradbeništvo je izredno razvejana in raznolika industrijska panoga, ki jo spremljajo številne spremembe in inovacije. Uporabljeni materiali, pogoji okolja, način gradnje, predvsem pa partnerji in izdelki se spreminjajo od projekta do projekta, po drugi strani pa lahko opazimo, da imajo gradbeni projekti tudi veliko skupnih značilnosti. Učinkovito upravljanje z znanjem v gradbenih podjetjih mora te posebnosti zaobjeti. V svetu so v zadnjih letih nastali številni modeli za upravljanje z znanjem. Z implementacijo različnih modelov si gradbeno podjetje lahko ustvari svoj sistem za zajemanje tako tihega kot eksplicitnega znanja in tako pripomore k večjemu poslovnemu uspehu ter prednosti pred konkurenco. Diplomsko delo predstavlja pomen in glavne značilnosti upravljanja z znanjem v gradbeništvu. Nadalje delo povzema nekatere izbrane modele za upravljanje z znanjem v gradbeni industriji, ki so opisani v literaturi. Analizirali smo tudi dve uspešni slovenski podjetji, pri katerih smo skušali s pomočjo izdelanega vprašalnika ter dobljenih odgovorov ugotoviti, v kolikšni meri je prisotno zavedanje pomembnosti upravljanja z znanjem in kako lahko s pomočjo le-tega njihovo poslovanje še izboljšajo. V obeh primerih se je izkazalo, da gre za sodobni podjetji, ki sledita svetovnim trendom in sta pripravljeni na tem področju graditi še naprej. Izdelek zaključujemo s predlogom obrazca o zajemu informacij iz izvedenega projekta, ki bi gradbenim podjetjem pomagal pri vgrajevanju povratnih informacij v naslednji projekt.Knowledge management could be viewed as an explicit and systematic approach to capturing information and knowledge about a company, its processes, products, services, markets, customers and competitors and then storing this in a place where relevant personnel can access, distribute it and make use of it. It is an ongoing and unique processit is management of intellectual capabilities, potentials and skills of people with the aim of improving performance and coping with change. Construction industry is an extremely complex sector accompanied by numerous changes and innovation. Materials, technologies, environmental conditions but most of all co-workers and finished products change from one project to anotheron the other hand, however, several common features can be observed in various construction projects. This has to be taken into account, if an efficient knowledge management in a construction company wants to be achieved. Several knowledge management models have been developed over the past years. A construction company needs to get acquainted with the different models in order to create its own system for acquiring both tacit and explicit knowledge, which contributes to improved business success and the company\u27s competitive edge. The thesis discusses the importance and main characteristics of knowledge management in construction. Selected knowledge management models applied to construction from the available literature are described. The analysis of two Slovenian construction companies is carried out by using a questionnaire. The obtained answers show that both companies are aware of the importance of knowledge management, and that they are willing to further develop this area. In the last part of the thesis, a draft form for data extraction is proposed that would enable the transfer of knowledge and experience from a completed project into a new one

Mixed Quantum/Classical Calculations of Rotationally Inelastic Scattering in the CO + CO System: A Comparison With Fully Quantum Results

An updated version of the CO + CO potential energy surface from [R. Dawes, X. G. Wang and T. Carrington, J. Phys. Chem. A 2013, 117, 7612] is presented, that incorporates an improved treatment of the asymptotic behavior. It is found that this new surface is only slightly different from the other popular PES available for this system in the literature [G. W. M. Vissers, P. E. S. Wormer and A. Van Der Avoird, Phys. Chem. Chem. Phys. 2003, 5, 4767]. The differences are quantified by expanding both surfaces over a set of analytic functions and comparing the behavior of expansion coefficients along the molecule–molecule distance R. It is shown that all expansion coefficients behave similarly, except in the very high energy range at small R where the PES is repulsive. That difference has no effect on low collision-energy dynamics, which is explored via inelastic scattering calculations carried out using the MQCT program which implements the mixed quantum/classical theory for molecular energy exchange processes. The validity of MQCT predictions of state-to-state transition cross sections for CO + CO is also tested by comparison against full-quantum coupled-states calculations. In all cases MQCT gives reliable results, except at very low collision energy where the full-quantum calculations predict strong oscillations of state-to-state transition cross sections due to resonances. For strong transitions with large cross sections, the results of MQCT are reliable, especially at higher collision energy. For weaker transitions, and lower collision energies, the cross sections predicted by MQCT may be up to a factor of 2–3 different from those obtained by full-quantum calculations

Inverse kinetic isotope effects in the charge transfer reactions of ammonia with rare gas ions

In the absence of experimental data, models of complex chemical environments rely on predicted reaction properties. Astrochemistry models, for example, typically adopt variants of capture theory to estimate the reactivity...</p