Vibrational Modes of the Van Der Waals-London Silicon Clusters Si2 and Si3 In the Gas-Phase

2019 ◽  
pp. 261-274
Author(s):  
Srećko Botrić ◽  
Ivan Zulim
Keyword(s):  
Gas Phase ◽  
Van Der Waals ◽  
Vibrational Modes ◽  
Silicon Clusters

scholarly journals Quantum dynamics of the ππ*/nπ* decay of the epigenetic nucleobase 1,5-dimethyl-cytosine in the gas phase

2020 ◽  
Vol 22 (45) ◽  
pp. 26525-26535
Author(s):  
Martha Yaghoubi Jouybari ◽  
Yanli Liu ◽  
Roberto Improta ◽  
Fabrizio Santoro
Keyword(s):  
Gas Phase ◽  
Quantum Dynamics ◽  
Vibrational Modes

A partial ultrafast ππ* → nπ* transfer is predicted. Many vibrational modes are activated, but oscillations of bonds and angles are quickly damped.

LASER-DRIVEN SYNTHESIS OF CARBON AND SILICON CLUSTERS FROM GAS-PHASE REACTANTS

1996 ◽  
Vol 03 (01) ◽  
pp. 807-811 ◽  
Author(s):  
M. EHBRECHT ◽  
H. FERKEL ◽  
V.V. SMIRNOV ◽  
O. STELMAKH ◽  
W. ZHANG ◽  
...  
Keyword(s):  
Gas Phase ◽  
Flow Reactor ◽  
Carbon Clusters ◽  
Molecular Flow ◽  
Silicon Cluster ◽  
Nanosized Particles ◽  
Silicon Clusters ◽  
Molecular Gases ◽  
Induced Decomposition ◽  
Cluster Beams

A newly developed technique is employed for the production of carbon and silicon cluster beams starting from gaseous compounds. It is based on the CO 2-laser-induced decomposition of molecular gases containing carbon and silicon, such as CO 2H2 and SiH 4, in a flow reactor. In order to decompose acetylene, SF 6 is used as a sensitizer. By introducing a skimmer into the reaction zone, the generated silicon and carbon clusters are transferred to free molecular flow and analyzed with a time-of-flight mass spectrometer. It is shown that the technique can be efficiently employed to produce fullerenes C 60 and C 70 and, in the case of silicon, ultrapure nanosized particles of up to 3-nm diameter.

STRUCTURAL, ELECTRONIC AND QSAR PROPERTIES OF THE CYFLUTHRIN MOLECULE: A THEORETICAL AM1 AND PM3 TREATMENT

2006 ◽  
Vol 17 (10) ◽  
pp. 1391-1402 ◽  
Author(s):  
EMİNE DENİZ ÇALIŞIR ◽  
ŞAKİR ERKOÇ
Keyword(s):  
Energy Level ◽  
Gas Phase ◽  
Ground State ◽  
Heat Of Formation ◽  
Tobacco Budworm ◽  
Vibrational Modes ◽  
Lumo Energy ◽  
Deciduous Fruit ◽  
Semi Empirical ◽  
Homo Energy Level

Cyfluthrin is a synthetic cyano-containing pyrethroid insecticide that has both contact and stomach poison action. It is a nonsystemic chemical used to control cutworms, ants, silverfish, cockroaches, mosquitoes, tobacco budworm and many others. Its primary agricultural uses have been for control of chewing and sucking insects on crops such as cotton, turf, ornamentals, hops, cereal, corn, deciduous fruit, peanuts, potatoes, and other vegetables. Cyfluthrin is also used in public health situations and for structural pest control. The structural, vibrational, electronic and QSAR properties of the cyfluthrin molecule in gas phase have been investigated theoretically by performing molecular mechanics method by using MM+ force field, and semi-empirical molecular orbital AM1 and PM3 calculations. The geometry of the molecule has been optimized, infrared spectrum (vibrational modes and intensities) and the electronic properties of the molecule have been calculated in its ground state. According to PM3 calculation, heat of formation of cyfluthrin molecule is about -48.58 kcal/mol (exothermic), which shows that this molecule thermodynamically be stable. The HOMO energy level for this molecule is found to be -9.701 eV and the LUMO energy level is -0.660 eV giving rise to a gap of 9.041 eV, which also indicates that cyfluthrin is thermodynamically stable.

scholarly journals Unknown Knowns: Case Studies in Uncertainties in the Computation of Thermochemical Parameters

2020 ◽  
Author(s):  
John Simmie
Keyword(s):  
Heat Capacity ◽  
Gas Phase ◽  
Basis Set ◽  
Statistical Thermodynamic ◽  
Vibrational Modes ◽  
Heavy Atoms ◽  
New Methods ◽  
Formation Enthalpies ◽  
Thermochemical Parameters

<div>Both the computation of, and the uncertainties associated, with gas-phase molar formation enthalpies are now quite well established for systems comprised of tens of ‘heavy’ atoms chosen from the commonest elements. The same cannot be said for derived thermochemical quantities such as entropy, heat capacity and an enthalpy function. Whilst the application of well known statistical thermodynamic relations is mostly understood, the determination of the uncertainty with which such values can be obtained has been little studied — apart, that is, for a general protocol devised by Goldsmith et al. [J. Phys. Chem. A, 2012, 116, 9033–9057]. Specific examples from that work are explored here and it is shown that their estimates are overly pessimistic. It is also evident that for some species the calculated thermochemical parameters show very little variation with either the level of theory, or basis set, or treatment of vibrational modes — this renders the inclusion of such species in databases designed to validate new methods of limited value.<br></div>

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