Multimolecular complexes of the phosphodiester anion with Zn( II ) or Mg( II ) and water molecules—Preliminary validations of a polarizable potential by ab initio quantum chemistry

2021 ◽  
Author(s):  
Nohad Gresh ◽  
David Perahia
Keyword(s):  
Quantum Chemistry ◽  
Ab Initio ◽  
Water Molecules

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.

Vibrational branching ratios and radiative lifetimes in the laser cooling of AlBr

2017 ◽  
Vol 19 (7) ◽  
pp. 5519-5524 ◽  
Author(s):  
Yufeng Gao ◽  
Mingjie Wan
Keyword(s):  
Quantum Chemistry ◽  
Ab Initio ◽  
Laser Cooling ◽  
Branching Ratios ◽  
Radiative Lifetimes

The feasibility of laser cooling of the AlBr molecule is investigated usingab initioquantum chemistry.

scholarly journals iSPECTRON : A simulation interface for linear and nonlinear spectra with ab‐initio quantum chemistry software

2021 ◽  
Vol 42 (9) ◽  
pp. 644-659 ◽  
Author(s):  
Francesco Segatta ◽  
Artur Nenov ◽  
Daniel R. Nascimento ◽  
Niranjan Govind ◽  
Shaul Mukamel ◽  
...  
Keyword(s):  
Quantum Chemistry ◽  
Ab Initio ◽  
Linear And Nonlinear

Theoretical investigation on spin-forbidden cooling transitions of gallium hydride

2017 ◽  
Vol 19 (36) ◽  
pp. 24647-24655 ◽  
Author(s):  
Yun-Guang Zhang ◽  
Hua Zhang ◽  
Hai-Yang Song ◽  
You Yu ◽  
Ming-Jie Wan
Keyword(s):  
Quantum Chemistry ◽  
Ab Initio ◽  
Theoretical Investigation ◽  
Laser Cooling ◽  
Gallium Hydride

The feasibility of laser cooling of gallium hydride is investigated using ab initio quantum chemistry.

scholarly journals QM AND AB INITIO INVESTIGATION ON THE HYDROGEN BONDING, NMR CHEMICAL SHIFTS AND SOLVENT EFFECTS ON THE DPPE

2010 ◽  
Vol 7 (3) ◽  
pp. 260-272
Author(s):  
M. Monajjemi ◽  
A. Nouri ◽  
H. Monajemi
Keyword(s):  
Hydrogen Bonding ◽  
Ab Initio ◽  
Atomic Orbital ◽  
Theoretical Data ◽  
Basis Sets ◽  
Stable Complex ◽  
Head Group ◽  
Water Molecules ◽  
Hartree Fock ◽  
Zwitterionic Form

The hydrogen bonding effects that were produced from interaction of membrane lipid dipalmitoylphosphatidyl-ethanolamine (DPPE) with 1-5 water molecules, has been theoretically  investigated through the quantum mechanical calculations at the Hartree-Fock level of theory and the 3-21G, 6-31G and 6-31G* basis sets with the computational package of Gaussian 98. According to the obtained results of the structural optimization of the isolated DPPE in the gas phase, we can see the evidences of interactions in the head group of this macromolecule (from the molecular point of view we have a proton transfer from the ammonium group to the phosphate oxygen of zwitterionic form. As we know that the hydrogen bonding of DPPE with water molecules which have surrounded its head group plays an important role in the permeability of DPPE. So, in order to understand the microscopic physico-chemical nature of this subject we have analyzed bond and torsion angles of DPPE before and after added water molecules.  In this paper we have theoretically studied the complexes DPPE with water molecules which have surrounded its head group. As mentioned before, this theoretically study has been done through Hartree-Fock level of theory by using simple basis sets. Theoretical data shows that the interaction of head group of DPPE with water molecules causes some changes in the geometry of DPPE which were explained by the contribution of zwitterionic form of DPPE macromolecule, and finally hydrated DPPE becomes stable complex. Comparison between theoretical and experimental geometry data of DPPE macromolecule shows that the calculation at the HF/3-21 level of theory produces results which they are in better agreement with the experimental data. Moreover the hydrogen bonding effects on the NMR shielding tensor of selected atoms in the hydrated complexes of DPPE were reported. The ";Gauge Including Atomic Orbitals"; (GIAO) approaches within the SCF-Hartree-Fock approximation have been used in order to investigate the influence of hydrogen bonding of DPPE-water complex on the shielding tensors. Finally, the solvent affects on the stability of DPPE macromolecule, dipole moment and atomic charge of some selected atoms of DPPE molecule was discussed using Onsager model and Merz-Singh-Kolman schema.   Keywords  : Gauge Including Atomic Orbital, DPPE, hydrogen bonding, solvation, quantum mechanics, ab initio

Ab Initio and DFT Study on Cyclophosphamide: Anticancer and Immunomodulating Agents

2018 ◽  
Vol 71 (7) ◽  
pp. 511 ◽  
Author(s):  
Giuseppe Bruno
Keyword(s):  
Ab Initio ◽  
Electronic Properties ◽  
Quantum Chemical ◽  
Immunosuppressive Agents ◽  
Water Molecules ◽  
Frontier Molecular Orbitals ◽  
Germ Cell Tumours ◽  
Antineoplastic Chemotherapy ◽  
Over Time ◽  
Ab Initio And Dft

Cyclophosphamide is presently the most frequently used drug for antineoplastic chemotherapy. It has shown a great response in the treatment of human malignancies including leukemia, lymphoma, germ cell tumours, medulloblastomas, and carcinomas of the breast, lung, and cervix. Cyclophosphamide is also one of the most important immunosuppressive agents. This study investigates the quantum-chemical electronic properties of cyclophosphamide, as well as some of its metabolites, which are computed using ab-initio and DFT calculations. The interaction energy calculations between water molecules and the cyclophosphamide show how, in the solid state, the presence of water of crystallisation will make cyclophosphamide more stable over time. Atomic charges, dipole moment, frontier molecular orbitals, electrostatic potential isosurface, geometric parameters, and proton affinity on every nitrogen site enable the characterisation of the electronic properties and clearly illustrate the reactive sites that could be associated with this biologically important class of molecules.

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