191 research outputs found
Cold reactive and non-reactive collisions of Li and Rb with C: implications for hybrid trap experiments
We present a theoretical investigation of cold reactive and non-reactive
collisions of Li and Rb atoms with C. The potential energy surfaces
for the singlet and triplet states of the Li--C and Rb--C
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 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 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(HO) with H and Rb: an ab initio study
We present a theoretical investigation of the hydrated hydroxide anion
clusters OH(HO) and of the collisional complexes
H-OH(HO) and Rb-OH(HO) (with n). 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 CHCN and CHNC with He : potential energy surfaces and low-energy scattering
Several nitrogen-bearing molecules, such as methyl cyanide (or acetonitrile,
CHCN) and methyl isocyanide (CHNC) 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 molecules at low temperatures. In this
work we compute new three-dimensional potential energy surfaces for the
CHNC-He and CHCN-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 and 58.61 cm for CHCN-He and
CHNC-He, respectively, while the dissociation energy of the complexes
are 18.64 and 18.65 cm, respectively. Low energy scattering calculations
of pure rotational (de-)excitation of CHCN and CHNC by collision with
He atoms are carried out with the close-coupling method and the collisional
cross sections of and CHNC and CHCN are computed for
kinetic energies up to 100 cm. While the PESs for both complexes are
qualitatively similar, that of CHNC-He is more anisotropic, leading to
different propensity rules for rotational excitation. For CHNC-He, we find
that || = 1 transitions are dominant at low kinetic energy and a
propensity rule that favors odd transitions is observed, whereas for
CHCN the dominant cross sections are associated to transitions with
|| = 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 , 19
, 12 , 9 , 4 and 2 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 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
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
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