scholarly journals A Post-HF Approach to the Sunscreen Octyl Methoxycinnamate

2021 ◽  
Author(s):  
Ettore Fois ◽  
Mario Oriani ◽  
gloria tabacchi
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Stable Isomer ◽  
Dispersion Interactions ◽  
Trans Form ◽  
Compact Structure ◽  
Hartree Fock ◽  
Molecular Dispersion ◽  
Cis And Trans ◽  
Effect Of Light

Octyl methoxycinnamate (OMC) is a commercial sunscreen with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as UVB filter. In particular, the trans (E) form - which is considered so far the most stable isomer - converts to the cis (Z) form under the effect of light. In this work, by using post-Hartree-Fock approaches (CCSD, CCSD(t) and CCSD+T(CCSD)) on ground state OMC geometries optimized at the MP2 level we show that the cis and trans form of the gas-phase OMC molecule have comparable stability. Our results suggest that the cis form is stabilized by intra-molecular dispersion interactions, leading to a folded, more compact structure than the trans isomer.<br>

scholarly journals A Post-HF Approach to the Sunscreen Octyl Methoxycinnamate

2021 ◽  
Author(s):  
Ettore Fois ◽  
Mario Oriani ◽  
gloria tabacchi
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Stable Isomer ◽  
Dispersion Interactions ◽  
Trans Form ◽  
Compact Structure ◽  
Hartree Fock ◽  
Molecular Dispersion ◽  
Cis And Trans ◽  
Effect Of Light

Octyl methoxycinnamate (OMC) is a commercial sunscreen with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as UVB filter. In particular, the trans (E) form - which is considered so far the most stable isomer - converts to the cis (Z) form under the effect of light. In this work, by using post-Hartree-Fock approaches (CCSD, CCSD(t) and CCSD+T(CCSD)) on ground state OMC geometries optimized at the MP2 level we show that the cis and trans form of the gas-phase OMC molecule have comparable stability. Our results suggest that the cis form is stabilized by intra-molecular dispersion interactions, leading to a folded, more compact structure than the trans isomer.<br>

scholarly journals A Post-HF Approach to the Sunscreen Octyl Methoxycinnamate

2021 ◽  
Author(s):  
Ettore Fois ◽  
Mario Oriani ◽  
gloria tabacchi
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Stable Isomer ◽  
Dispersion Interactions ◽  
Trans Form ◽  
Compact Structure ◽  
Hartree Fock ◽  
Molecular Dispersion ◽  
Cis And Trans ◽  
Effect Of Light

Octyl methoxycinnamate (OMC) is a commercial sunscreen with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as UVB filter. In particular, the trans (E) form - which is considered so far the most stable isomer - converts to the cis (Z) form under the effect of light. In this work, by using post-Hartree-Fock approaches (CCSD, CCSD(t) and CCSD+T(CCSD)) on ground state OMC geometries optimized at the MP2 level we show that the cis and trans form of the gas-phase OMC molecule have comparable stability. Our results suggest that the cis form is stabilized by intra-molecular dispersion interactions, leading to a folded, more compact structure than the trans isomer.<br>

scholarly journals Negative ion photoelectron spectroscopy confirms the prediction that D3h carbon trioxide (CO3) has a singlet ground state

2016 ◽  
Vol 7 (2) ◽  
pp. 1142-1150 ◽  
Author(s):  
David A. Hrovat ◽  
Gao-Lei Hou ◽  
Bo Chen ◽  
Xue-Bin Wang ◽  
Weston Thatcher Borden
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Radical Anion ◽  
Negative Ion ◽  
Singlet Ground State

The CO3 radical anion (CO3˙−) has been formed by electrospraying carbonate dianion (CO32−) into the gas phase.

Correlation in the Ground State of He Atom

1981 ◽  
Vol 36 (3) ◽  
pp. 272-275 ◽  
Author(s):  
Subal Chandra Saha ◽  
Sankar Sengupta
Keyword(s):  
Ground State ◽  
Zero Order ◽  
Consistent Variation ◽  
Hartree Fock ◽  
Perturbation Procedure ◽  
Self Consistent ◽  
He Atom ◽  
Atomic Parameters

It is possible to reproduce the entire results of Pekeris et al. of different atomic parameters for the He atom by introducing (ll) type correlation in a self consistent variation perturbation procedure using the Hartree-Fock (HF) wavefunction as the zero-order wavefunction

Near Hartree-Fock relative energies of cis- and trans-1,2-difluoroethylene

1986 ◽  
Vol 125 (5-6) ◽  
pp. 447-450 ◽  
Author(s):  
David A. Dixon ◽  
Bruce E. Smart ◽  
Tadamichi Fukunaga
Keyword(s):  
Hartree Fock ◽  
Cis And Trans

scholarly journals THE METHOD OF INCREMENTS — A WAVEFUNCTION-BASED AB-INITIO CORRELATION METHOD FOR SOLIDS

2007 ◽  
Vol 21 (13n14) ◽  
pp. 2204-2214 ◽  
Author(s):  
BEATE PAULUS
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Ground State ◽  
Infinite System ◽  
Correlation Energy ◽  
Correlation Method ◽  
Many Body ◽  
Hartree Fock ◽  
The Many ◽  
Good Agreement

The method of increments is a wavefunction-based ab initio correlation method for solids, which explicitly calculates the many-body wavefunction of the system. After a Hartree-Fock treatment of the infinite system the correlation energy of the solid is expanded in terms of localised orbitals or of a group of localised orbitals. The method of increments has been applied to a great variety of materials with a band gap, but in this paper the extension to metals is described. The application to solid mercury is presented, where we achieve very good agreement of the calculated ground-state properties with the experimental data.

The Dielectric Discharge as an Efficient Generator of Active Nitrogen for Chemiluminescence and Analysis

1983 ◽  
Vol 37 (6) ◽  
pp. 545-552 ◽  
Author(s):  
John Kishman ◽  
Eric Barish ◽  
Ralph Allen
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Band System ◽  
Electrothermal Atomization ◽  
Characteristic Radiation ◽  
Gaseous Species ◽  
Vibrationally Excited ◽  
Active Nitrogen ◽  
Excited Species ◽  
Intense Emission

A predominantly blue “active nitrogen” afterglow was generated in pure flowing nitrogen or in air by using a dielectric discharge at pressures from 1 to 20 Torr. The afterglow contains triplet state molecules and vibrationally excited ground state molecules. These species are produced directly by electron impact without the formation and recombination of nitrogen atoms. The most intense emission is the N2 second positive band system. The N2 first positive and N2+ first negative systems are also observed. The spectral and electrical properties of this discharge are discussed in order to establish guidelines for the analytical use of the afterglow for chemiluminescence reactions. The metastatic nitrogen efficiently transfers its energy to atomic and molecular species which are introduced into the gas phase and these excited species emit characteristic radiation. The effects of electrothermal atomization of Zn and the introduction of gaseous species (e.g., NO) on the afterglow are described.

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