Stable Structures of Donor-Acceptor-Donor Trimer Codopants in 4H-SiC

2013 ◽  
Vol 718-720 ◽  
pp. 37-41
Author(s):  
Naoyuki Nishio ◽  
Masanori Miyata ◽  
Yoshinori Hayafuji
Keyword(s):  
Ab Initio ◽  
Concentration Ratio ◽  
Binding Energies ◽  
Donor Acceptor ◽  
Total Energies ◽  
Formation Energies ◽  
Doping Condition ◽  
Stable Structures

The total energies of 4H-SiC with donor-acceptor-donor (D2A) trimer codopants (D = N, P, As, and Sb, A = B, Al, Ga, and In), the formation energies of D2A, DA, D, and A species and the binding energies were studied usingab initiocalculations in order to determine the stable structures of D2A trimer codopants in 4H-SiC. The results of the calculations indicated that some of the trimer codopants were formed and were stable in 4H-SiC. In particular, N2Al, N2Ga and N2In trimer codopants with N(Ch)-Al/Ga/In (Sik)-N(Ch) configuration and As2B trimer codopants with As (Sih)-B(Ck)-As (Sih) configuration stably exist in 4H-SiC under the doping condition wherein the concentration ratio of donors to acceptors is 2 : 1.

Gas and solution phase thermochemistry and transition energies of NH2• and NH3•+, and their aquo complexes: an ab initio study

1994 ◽  
Vol 72 (3) ◽  
pp. 471-483 ◽  
Author(s):  
Dake Yu ◽  
Arvi Rauk ◽  
David A. Armstrong
Keyword(s):  
Ab Initio ◽  
Binding Energies ◽  
Solution Phase ◽  
Interaction Energies ◽  
Free Energies ◽  
Transition Energies ◽  
Bonding Interaction ◽  
Ab Initio Structure ◽  
Total Energies ◽  
Free Energy Of Solution

Ab initio calculations were performed on several aquo complexes of NH2•, and NH3•+, and on monomeric parent species. The geometries were optimized at the HF/6-31 + G* level and the vibrational frequencies were calculated. The total energies and the binding energies of complexes were evaluated at the MP2/6-31 + G* + ZPE level of theory. Gas and aqueous solution phase thermodynamic properites of NH2• and NH3•+ and several other species were calculated. The examination of solution phase properties of the radicals was facilitated by study of the structures and transition energies of aquo complexes. H-bonding interaction energies decreased in the order [Formula: see text] but were generally stronger than σ–σ* interactions involving the unpaired electron. From calculations with the CIS method, the weak absorption observed at 520 nm for aqueous NH2• is confirmed as a 2B1 → 2A1 transition, while the stronger NH2• absorption occurring below 250 nm and the absorption of NH3•+, which rises monotonically below 370 nm, are attributed to solvent-to-solute charge transfer bands. The solution free energies and related E0 values for NH2• and NH3•+ are in agreement with those of Stanbury. The ab initio structure studies show that water protons are bound to N, and proton transfer from solvent in reaction [18], NH2• + e− + H2O → NH3 + OH−, is likely to be the dominant redox reaction of NH2• in alkaline solution. The free energy of solution of NH3•+ is shown to be larger than that of [Formula: see text].

scholarly journals Nature of the Interaction of Pyridines with OCS. A Theoretical Investigation

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 416 ◽  
Author(s):  
Sumitra Bhattarai ◽  
Dipankar Sutradhar ◽  
Asit K. Chandra ◽  
Therese Zeegers-Huyskens
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Frequency Shift ◽  
Theoretical Investigation ◽  
Electrostatic Potential ◽  
Binding Energies ◽  
Vibrational Modes ◽  
Substituted Pyridines ◽  
Stable Structures

Ab initio calculations were carried out to investigate the interaction between para-substituted pyridines (X-C5H4N, X=NH2, CH3, H, CN, NO2) and OCS. Three stable structures of pyridine.OCS complexes were detected at the MP2=full/aug-cc-pVDZ level. The A structure is characterized by N…S chalcogen bonds and has binding energies between −9.58 and −12.24 kJ/mol. The B structure is bonded by N…C tetrel bond and has binding energies between −10.78 and −11.81 kJ/mol. The C structure is characterized by π-interaction and has binding energies between −10.76 and −13.33 kJ/mol. The properties of the systems were analyzed by AIM, NBO, and SAPT calculations. The role of the electrostatic potential of the pyridines on the properties of the systems is outlined. The frequency shift of relevant vibrational modes is analyzed.

Electronic Structures of Donor-Acceptor-Donor Trimer Codopants in Silicon

2011 ◽  
Vol 216 ◽  
pp. 402-407 ◽  
Author(s):  
Nobuo Kambara ◽  
Hiroyuki Kawanishi
Keyword(s):  
Ab Initio Calculations ◽  
Electronic Structures ◽  
Solid Solubility ◽  
Single Donor ◽  
Shallow Junctions ◽  
Donor Acceptor ◽  
High Carrier ◽  
Total Energies ◽  
Ultra Shallow Junctions ◽  
Stable Structures

The total energies of donor-acceptor-donor D2A trimer codopants (D = As and Sb, A = B, Al, Ga, In and Tl) in Si and their electronic geometrically stable structures were studied using ab initio calculations in order to propose new dopants for the formation of ultra shallow junctions with high carrier concentrations in the source/drain regions. The results of the calculations indicated that the trimer codopants were formed in Si and were stable. The trimer codopants are also able to activate the inactive complexes As2V and Sb2V by codoping acceptor atoms that occupy vacant sites. In particular, As2Al, As2Ga, Sb2B and Sb2Ga resulted in both shallower donor levels and higher solid solubility compared to traditional single donor atoms such as As and Sb.

Amorphous Si1−yCy composite anode materials: ab initio molecular dynamics for behaviors of Li and Na in the framework

2021 ◽  
Author(s):  
Jaewoong Hur
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Anode Materials ◽  
Ab Initio Molecular Dynamics ◽  
Composite Anode ◽  
Formation Energies

Random configurations and formation energies of a-MxSi1−yCy frameworks at x = 3.0 of Li and x = 0.5 of Na contents.

First-Principles Analysis on Interaction between Dopant (Ga, Sb) and Contamination Metal Atoms in Ge Crystals

2013 ◽  
Vol 205-206 ◽  
pp. 417-421
Author(s):  
Tatsunori Yamato ◽  
Koji Sueoka ◽  
Takahiro Maeta
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Binding Energies ◽  
Functional Theory ◽  
Substitutional Site ◽  
Metal Impurities ◽  
Metal Atoms ◽  
Total Energies ◽  
Group 3

The lowest energetic configurations of metal impurities in 4throw (Sc - Zn), 5throw (Y - Cd) and 6throw (Hf - Hg) elements in Ge crystals were determined with density functional theory calculations. It was found that the substitutional site is the lowest energetic configuration for most of the calculated metals in Ge. The most stable configurations of dopant (Ga, Sb) - metal complexes in Ge crystals were also investigated. Following results were obtained. (1) For Ga dopant, 1st neighbor T-site is the most stable for metals in group 3 to 7 elements while substitutional site next to Ga atom is the most stable for metals in group 8 to 12 elements. (2) For Sb dopant, substitutional site next to Sb atom is the most stable for all calculated metals. Binding energies of the interstitial metalMiwith the substitutional dopantDswere obtained by the calculated total energies. The calculated results for Ge were compared with those for Si.

scholarly journals Stable Occupancy of Hydrogen Molecules in Clathrate Hydrates and + THF Clathrate Hydrates Determined by Ab Initio Calculations

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Prasad Yedlapalli ◽  
Sangyong Lee ◽  
Jae W. Lee
Keyword(s):  
Ab Initio ◽  
Binding Energies ◽  
Clathrate Hydrates ◽  
Basis Set ◽  
Large Cavity ◽  
Basis Sets ◽  
Pure Hydrogen ◽  
Point Energy ◽  
Small Cavity ◽  
Hydrogen Molecules

Structure II clathrate hydrates of pure hydrogen and binary hydrates of are studied using ab initio calculations to determine the stable occupancies of small cavities. Ab initio calculations are carried out for a double cavity consisting of one dodecahedron (small cavity) and one hexakaidecahedron (large cavity). These two cavities are attached to each other as in sII hydrates to form a double cavity. One or two molecules are placed in the small cavity and one THF (or 4 molecules) molecule is placed in the large cavity. We have determined the binding energies of the double cavities at the MP2 level using various basis sets (3-21G, 3-21G(2p), 3-21 G(2p), 6-31G, 6-31G(2p), and 6-31 G(2p)). Different basis sets yield different stable occupancies of the small cavity. The results from the highest basis set (6-31 G(2p) with zero point energy corrections) indicate that the single occupancy is slightly more favorable than the double occupancy in both the cases of pure hydrates and THF + double hydrates.

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