A density functional study of the bonding in tertiary phosphine chalcogenides and related molecules

1996 ◽  
Vol 74 (11) ◽  
pp. 2363-2371 ◽  
Author(s):  
Nicole Sandblom ◽  
Tom Ziegler ◽  
Tristram Chivers
Keyword(s):  
Density Functional ◽  
Functional Study ◽  
Single Bond ◽  
Bond Energies ◽  
Tertiary Phosphine ◽  
Functional Theory ◽  
Multiple Bonding ◽  
Back Donation ◽  
Oxygen Bond ◽  
Phosphine Chalcogenides

The nature of the phosphorus–tellurium bond in tertiary phosphine tellurides is not well understood. There is also controversy over the nature of multiple bonding in the lighter chalcogenides and the related ylides and imides. Density functional theory (DFT) was used to investigate the interactions in the molecule, Me3PE (E = O, S, Se, Te, BH3, CH2, NH). The calculated PE bond energies and orbital populations reveal contributions from both σ donation from the phosphine and π back-donation to the phosphine in all of the above cases. Down the group from oxygen to tellurium, the PE bond weakens from 544 kJ mol−1 to 184 kJ mol−1, but multiple bonding becomes more significant with respect to the single bond. For E = BH3, the PB bond energy is 166 kJ mol−1. Trimethylphosphine ylide was found to have a π-bond order of 0.5, while that of trimethylphosphine imine is 0.6. For comparison, the oxides of trimethylamine and trimethylarsine were also calculated to examine the pnictogen–oxygen bond; Me3N does not participate in multiple bonding with oxygen, while the π-bond orders for Me3PO and Me3AsO were calculated as 0.7 and 0.6, respectively. Key words: phosphine chalcogenides, phosphine ylides, phosphine imides, DFT calculations

Pyrolysis behaviors of polyethylene terephthalate (PET): A density functional study

2021 ◽  
Vol 35 (04) ◽  
pp. 2150048
Author(s):  
Jiawei Zhang ◽  
Fei Yan
Keyword(s):  
Polyethylene Terephthalate ◽  
Density Functional ◽  
Ethylene Terephthalate ◽  
Functional Study ◽  
Carboxyl Groups ◽  
Single Bond ◽  
Functional Theory ◽  
Pyrolysis Mechanism ◽  
Dissociation Energies ◽  
Cyclic Compounds

In this paper, the pyrolysis mechanism of polyethylene terephthalate (PET), which accounts for a large proportion in plastics component, is investigated by density functional theory (DFT). The dissociation energies of the several important bonds in PET are calculated. The results indicate that the C–C bond between two carboxyl groups in ethylene terephthalate is very weak, followed by the single bond between carboxyl group and carbon atom. The kinetic analysis shows the energy barriers of the reactions to release CO2 are stable while that of CO fluctuates. In addition, the reaction paths of the formation of cyclic compounds are proposed.

A Combined ab initio and Density Functional Study of the Electronic Structure of Thymine and 2-Thiothymine Radicals

2003 ◽  
Vol 68 (12) ◽  
pp. 2322-2334 ◽  
Author(s):  
Robert Vianello ◽  
Zvonimir B. Maksić
Keyword(s):  
Ab Initio ◽  
Spin Density ◽  
Density Functional ◽  
Radical Cations ◽  
Functional Study ◽  
Theory Approach ◽  
Functional Theory ◽  
Adiabatic Ionization Potential ◽  
Highest Occupied Molecular Orbital ◽  
Positively Charged

The electronic and energetic properties of thymine (1) and 2-thiothymine (2) and their neutral and positively charged radicals are considered by a combined ab initio and density functional theory approach. It is conclusively shown that ionization of 1 and 2 greatly facilitates deprotonation of the formed radical cations thus making the proton transfer between charged and neutral precursor species thermodynamically favourable. The adiabatic ionization potential of 1 and 2 are analysed. It appears that ADIP(1) is larger than ADIP(2) by 10 kcal/mol, because of greater stability of the highest occupied molecular orbital (HOMO) of the former. It is also shown beyond any doubt that the spin density in neutral and cationic radical of 2 is almost exclusively placed on the σ-3p AO of sulfur implying that these two systems represent rather rare sigma-radicals. In contrast, the spin density of radicals of 1 is distributed over their π-network.

A DENSITY FUNCTIONAL STUDY OF THE STRUCTURE OF SILANE COUPLING AGENT 3–AMINOPROPYLTRIETHOXYSILANE

2005 ◽  
Vol 04 (01) ◽  
pp. 117-126
Author(s):  
N. L. MA ◽  
P. WU
Keyword(s):  
Coupling Agent ◽  
Density Functional ◽  
Solution Structure ◽  
Silane Coupling Agent ◽  
Industrial Applications ◽  
Functional Study ◽  
Stable Form ◽  
Functional Theory ◽  
Silane Coupling ◽  
The Stability

Using density functional theory, we predicted the solution structure of the hydrolyzed 3–aminopropyltriethoxysilane (h–APS), which is a silane coupling agent commonly used in many industrial applications. We have located five stable minima on the potential energy surface of h–APS in which four of them are "neutral", and the remaining one is zwitterionic (dipolar) in nature. Our calculations suggested that the stability of the most stable form of h–APS in water (denoted as II_N) arose from strong intramolecular OH ⋯ N hydrogen bond. The least stable form is the zwitterionic form (I_ZW), which is estimated to be over 90 kJ mol -1 less stable than II_N. The factors governing the relative stabilities of different forms are discussed.

scholarly journals Na-ion diffusion in a NASICON-type solid electrolyte: a density functional study

2016 ◽  
Vol 18 (39) ◽  
pp. 27226-27231 ◽  
Author(s):  
Kieu My Bui ◽  
Van An Dinh ◽  
Susumu Okada ◽  
Takahisa Ohno
Keyword(s):  
Density Functional Theory ◽  
Solid Electrolyte ◽  
Electronic Structures ◽  
Density Functional ◽  
Diffusion Mechanism ◽  
Functional Study ◽  
Ion Diffusion ◽  
Functional Theory ◽  
Density Functional Study ◽  
Nasicon Type

Based on density functional theory, we have systematically studied the crystal and electronic structures, and the diffusion mechanism of the NASICON-type solid electrolyte Na3Zr2Si2PO12.

scholarly journals Theoretical Study of Thermal Cracking For Acenaphthylene Molecule

2013 ◽  
Vol 10 (3) ◽  
pp. 1071-1081
Author(s):  
Baghdad Science Journal
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Reaction Path ◽  
Polyaromatic Hydrocarbons ◽  
Thermal Cracking ◽  
Triplet States ◽  
Bond Energies ◽  
Functional Theory ◽  
Repulsion Energy ◽  
Bond Breakage

Density Functional Theory (DFT) calculations were carried out to study the thermal cracking for acenaphthylene molecule to estimate the bond energies for breaking C8b-C5a , C5a-C5 , C5-C4 , and C5-H5 bonds as well as the activation energies. It was found that for C8b-C5a , C5-C4 , and C5-H5 reactions it is often possible to identify one pathway for bond breakage through the singlet or triplet states. The atomic charges , dipole moment and nuclear – nuclear repulsion energy supported the breakage bond .Also, it was found that the activation energy value for C5-H5 bond breakage is lower than that required for C8b-C5a , C5a-C5 , C5-C4 bonds which refer to C5-H5 bond in acenaphthylene molecule are weaker than C8b-C5a , C5a-C5 , C5-C4 bonds .It is reasonable to presume that C5-H5 bonds are broken first when a acenaphthylene molecule is exposed to thermal cracking. It seems that the characteristic planarity for the polyaromatic hydrocarbons is an important factor to acquire the molecule structure of the required stability along the reaction path . The trends in the bond energies and the configuration structures are discussed .

A Density Functional Study of PdCn(n= 2-12) Clusters

2013 ◽  
Vol 652-654 ◽  
pp. 815-818
Author(s):  
Yan Wei ◽  
Jia Xin Xu ◽  
Xiao Mei Yuan ◽  
Xiao Hui Zheng
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Density Functional ◽  
Turning Point ◽  
Functional Study ◽  
Functional Theory ◽  
Density Functional Study ◽  
The Density Functional Theory

We have studied the structures and electronic properties of PdCn (n=2-12) using the density functional theory in this paper. Though calculating, we found that the linear isomers are most stable for PdCn(n=2-9) clusters. N=10 is turning point, and the bicyclical structure is most stable for PdC10 cluster. Cyclic structures have the lowest energy for PdC11 and PdC12 clusters.

Density Functional Theory Study of the Role of an Carbon–Oxygen Single Bond Group in the NO–Char Reaction

2018 ◽  
Vol 32 (7) ◽  
pp. 7734-7744 ◽  
Author(s):  
Tong Zhao ◽  
Wenli Song ◽  
Chuigang Fan ◽  
Songgeng Li ◽  
Peter Glarborg ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Single Bond ◽  
Density Functional Theory Study ◽  
Functional Theory

CO2 Adsorption on the B12N12 Nanocage Encapsulated with Alkali Metals: A Density Functional Study

NANO ◽  
2019 ◽  
Vol 14 (03) ◽  
pp. 1950034
Author(s):  
Ximin Liang ◽  
Qiyan Zhang ◽  
Qinfu Zhao ◽  
He Zhao ◽  
Yifan Feng ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Density Functional ◽  
Alkali Metals ◽  
Large Change ◽  
Functional Study ◽  
Functional Theory ◽  
Metal Atoms ◽  
Adsorption Of Co ◽  
Physical And Chemical ◽  
Homo Lumo

Density functional theory (DFT) calculations have been carried out to study the capacity of the B[Formula: see text]N[Formula: see text] nanocage encapsulated with alkali metals (Li, Na, K) for the CO2 adsorption and activation. It is found that after encapsulating alkali metals, the alkali metal atoms are closer to one side of clusters instead of exactly lying at the center, and a considerable charge transfers from the inner alkali metal atoms to the B[Formula: see text]N[Formula: see text] cage. Besides, the HOMO–LUMO gap (HLG) values of Li@B[Formula: see text]N[Formula: see text], Na@B[Formula: see text]N[Formula: see text] and K@B[Formula: see text]N[Formula: see text] are decreased to about 6[Formula: see text]eV, being much smaller than that of the pristine B[Formula: see text]N[Formula: see text]. Although the geometry structure parameters and the energy differences of M06-2X are slightly different from the ones of [Formula: see text]B97X-D, some identical results of two kinds of functional can be obtained. CO2 can be adsorbed chemically and physically on majority bonds of all the clusters, except for some bonds with large change in bond length and bond indices. The encapsulation of alkali-metal atoms may enhance the physical and chemical adsorption of CO2 on the surface of the clusters, in which Na@B[Formula: see text]N[Formula: see text] and K@B[Formula: see text]N[Formula: see text] are the most powerful physical and chemical adsorbent for CO2, respectively.

TIME-DEPENDENT DENSITY FUNCTIONAL STUDY OF MULTIELECTRON TRANSFER IN Cq+–Na4 COLLISIONS

2010 ◽  
Vol 24 (24) ◽  
pp. 4811-4820
Author(s):  
Y. P. ZHANG ◽  
F. S. ZHANG ◽  
Y. GAO ◽  
H. W. CHANG ◽  
G. Q. XIAO
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Time Dependent ◽  
Functional Study ◽  
Density Approximation ◽  
Functional Theory ◽  
The Difference ◽  
Multielectron Transfer ◽  
Dependent Density

The process of multielectron transfer from a Na 4 cluster induced by highly charged C 6+, C 4+, C 2+ and C + ions is studied using the method of time-dependent density functional theory within the local density approximation combined with the use of pseudopotential. The evolution of dipole moment changes and emitted electrons in Na 4 is obtained and the time-dependent probabilities with various charges are deduced. It is shown that the Na 4 cluster is strongly ionized by C 6+ and that the number of emitted electrons per atom of Na 4 is larger than that of Na 2 under the same condition. One can find that the detailed information of the emitted electrons from Na 4 is different from the same from Na 2, which is possibly related to the difference in structure between the two clusters.

Density Functional Study of H2S Adsorption on Small Agn (n = 1–5)

2013 ◽  
Vol 634-638 ◽  
pp. 47-51 ◽  
Author(s):  
Jun Qing Wen ◽  
A Ping Yang ◽  
Guo Xiang Chen ◽  
Chen Jun Zhang
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Global Minimum ◽  
Electronic States ◽  
Functional Study ◽  
Functional Theory ◽  
Energy Gaps ◽  
Single Fold ◽  
Homo And Lumo

The global-minimum geometries and electronic states of AgnH2S (n=1-5) clusters have been calculated using density-functional theory. Our calculations predicate that the stable geometries of AgnH2S clusters can be got by directly adding the H2S molecule on different site of Agn clusters, Agn (n=1-5) clusters would like to bond with sulfur atom and the H2S molecule is partial to hold the top location and single fold coordination site in the clusters. After adsorption, the structures of Agn clusters and H2S molecule keep the original structures and are only distorted slightly. The averaged binding energy reveals that adsorption of H2S molecule can strengthen the stabilities of AgnH2S clusters. The second difference in energy and the energy gaps between the HOMO and LUMO of Agn and AgnH2S have been studied.

Sign in / Sign up

Export Citation Format

Share Document