Ab initio theoretical calculations of the electronic excitation energies of small water clusters

2011 ◽  
Vol 13 (46) ◽  
pp. 20745 ◽  
Author(s):  
Hiroto Tachikawa ◽  
Akihiro Yabushita ◽  
Masahiro Kawasaki
Keyword(s):  
Ab Initio ◽  
Electronic Excitation ◽  
Water Clusters ◽  
Theoretical Calculations ◽  
Excitation Energies ◽  
Small Water

Stable numerical methods for determination of the molecular clusters force fields

2020 ◽  
Vol 28 (5) ◽  
pp. 621-631
Author(s):  
Gulnara M. Kuramshina ◽  
Alexander A. Zakharov
Keyword(s):  
Inverse Problem ◽  
Ab Initio ◽  
Water Clusters ◽  
Force Fields ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Small Water ◽  
Molecular Force ◽  
The Given

AbstractThe inverse problem of molecular force fields calculation is considered within the theory of regularization. In our strategy, we choose the stabilizing matrix F^{0} as a result of quantum mechanical calculations. The solution of the inverse problem is finding a matrix 𝐹 which is the nearest by the chosen Euclidean norm to the given ab initio F^{0}. The optimized solution is referred to as regularized quantum mechanical force field (RQMFF). Regularizing algorithms of molecular force fields calculation based on the joint treatment of experimental and ab initio quantum mechanical data have been applied to the calculations of molecular force fields (matrices of force constants) for small water clusters (H2O)𝑛 (n=2,3).

The Lyman and Werner Bands of Deuterium

1973 ◽  
Vol 51 (9) ◽  
pp. 867-887 ◽  
Author(s):  
H. Bredohl ◽  
G. Herzberg
Keyword(s):  
High Resolution ◽  
Ab Initio Calculations ◽  
Vibrational Level ◽  
Ground State ◽  
Electronic Excitation ◽  
Theoretical Calculations ◽  
Dissociation Limit ◽  
Excitation Energies ◽  
Vibrational Levels ◽  
Theory And Experiment

The Lyman and Werner bands of D2 have been measured under high resolution and their analysis has been extended. From this analysis the rotational and vibrational levels of the ground state of D2 have been evaluated up to the last vibrational level ν = 21 which lies only 2 cm−1 below the dissociation limit. The deviations of the observed ΔG(ν + 1/2) and Bv values from theoretical values given by Kolos and Wolniewicz on the basis of ab initio calculations are very small but systematic and are probably due to the neglect of nonadiabatic corrections in the theoretical calculations. Similar comparisons have been made for the lower vibrational levels of the B1Σu+ and C1Πu− states. Here the differences between theory and experiment are somewhat larger. The observed electronic excitation energies agree with the theoretical ones within 15 cm−1 for 1Σu+ and 8 cm−1 for 1Πu−.

Thermodynamic Data of Iodine Reactions Calculated by Quantum Chemistry. Training Set of Molecules

2008 ◽  
Vol 73 (10) ◽  
pp. 1340-1356 ◽  
Author(s):  
Katarína Mečiarová ◽  
Laurent Cantrel ◽  
Ivan Černušák
Keyword(s):  
Quantum Chemistry ◽  
Ab Initio ◽  
Thermodynamic Data ◽  
Theoretical Calculations ◽  
Reactor Core ◽  
Fission Products ◽  
Vapour Phase ◽  
Reactor Accident ◽  
Training Set ◽  
Coolant System

This paper focuses on the reactivity of iodine which is the most critical radioactive contaminant with potential short-term radiological consequences to the environment. The radiological risk assessments of 131I volatile fission products rely on studies of the vapour-phase chemical reactions proceeding in the reactor coolant system (RCS), whose function is transferring the energy from the reactor core to a secondary pressurised water line via the steam generator. Iodine is a fission product of major importance in any reactor accident because numerous volatile iodine species exist under reactor containment conditions. In this work, the comparison of the thermodynamic data obtained from the experimental measurements and theoretical calculations (approaching "chemical accuracy") is presented. Ab initio quantum chemistry methods, combined with a standard statistical-thermodynamical treatment and followed by inclusion of small energetic corrections (approximating full configuration interaction and spin-orbit effects) are used to calculate the spectroscopic and thermodynamic properties of molecules containing atoms H, O and I. The set of molecules and reactions serves as a benchmark for future studies. The results for this training set are compared with reference values coming from an established thermodynamic database. The computed results are promising enough to go on performing ab initio calculations in order to predict thermo-kinetic parameters of other reactions involving iodine-containing species.

Electronic Excitation Energies of ZniOiClusters

2003 ◽  
Vol 125 (31) ◽  
pp. 9494-9499 ◽  
Author(s):  
Jon M. Matxain ◽  
Jose M. Mercero ◽  
Joseph E. Fowler ◽  
Jesus M. Ugalde
Keyword(s):  
Electronic Excitation ◽  
Excitation Energies
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