CLB18: A New Structural Database with Unusual Carbon–Carbon Long Bonds

2020 ◽  
Author(s):  
Pierpaolo Morgante ◽  
Roberto Peverati
Keyword(s):  
Transition Metal Complexes ◽  
Low Cost ◽  
Geometry Optimization ◽  
Structure Calculation ◽  
Unique Property ◽  
Spin States ◽  
Calculation Methods ◽  
Large Molecules ◽  
Barrier Heights ◽  
Structural Database

<div><div><div><p>In this Letter, we introduce a new database called carbon long bond 18 (CLB18), composed of 18 structures with one long C–C bond. We use this new database to evaluate the performance of several low-cost methods commonly used for geometry optimization of medium and large molecules. We found that the long bonds in CLB18 are electronically different from those found in barrier heights databases. We also report the unexpected correlation between the results of CLB18 and those of the energetics of spin states in transition-metal complexes. Given this unique property, CLB18 can be a useful tool for assessing existing electronic structure calculation methods and developing new ones.</p></div></div></div>

CLB18: A New Structural Database with Unusual Carbon–Carbon Long Bonds

2020 ◽  
Author(s):  
Pierpaolo Morgante ◽  
Roberto Peverati
Keyword(s):  
Transition Metal Complexes ◽  
Low Cost ◽  
Geometry Optimization ◽  
Structure Calculation ◽  
Unique Property ◽  
Spin States ◽  
Calculation Methods ◽  
Large Molecules ◽  
Barrier Heights ◽  
Structural Database

<div><div><div><p>In this Letter, we introduce a new database called carbon long bond 18 (CLB18), composed of 18 structures with one long C–C bond. We use this new database to evaluate the performance of several low-cost methods commonly used for geometry optimization of medium and large molecules. We found that the long bonds in CLB18 are electronically different from those found in barrier heights databases. We also report the unexpected correlation between the results of CLB18 and those of the energetics of spin states in transition-metal complexes. Given this unique property, CLB18 can be a useful tool for assessing existing electronic structure calculation methods and developing new ones.</p></div></div></div>

XO: An extended ONIOM method for accurate and efficient geometry optimization of large molecules

2010 ◽  
Vol 498 (1-3) ◽  
pp. 203-208 ◽  
Author(s):  
Wenping Guo ◽  
Anan Wu ◽  
Xin Xu
Keyword(s):  
Geometry Optimization ◽  
Large Molecules ◽  
Oniom Method

Sol-gel-derived gallium nitride thin films for ultraviolet photodetection

2019 ◽  
Vol 36 (1) ◽  
pp. 8-13 ◽  
Author(s):  
Chee Yong Fong ◽  
Sha Shiong Ng ◽  
NurFahana Mohd Amin ◽  
Fong Kwong Yam ◽  
Zainuriah Hassan
Keyword(s):  
Thin Films ◽  
Dark Current ◽  
Uv Light ◽  
Low Cost ◽  
Sol Gel ◽  
Contrast Ratio ◽  
Uv Photodetector ◽  
Content Type ◽  
Barrier Heights ◽  
Coating Method

Purpose This study aims to explore the applicability of the sol-gel-derived GaN thin films for UV photodetection. Design/methodology/approach GaN-based ultraviolet (UV) photodetector with Pt Schottky contacts was fabricated and its applicability was investigated. The current-voltage (I-V) characteristics of the GaN-based UV photodetector under the dark current and photocurrent were measured. Findings The ideality factors of GaN-based UV photodetector under dark current and photocurrent were 6.93 and 5.62, respectively. While the Schottky barrier heights (SBH) for GaN-based UV photodetector under dark current and photocurrent were 0.35 eV and 0.34 eV, respectively. The contrast ratio and responsivity of this UV photodetector measured at 5 V were found to be 1.36 and 1.68 μA/W, respectively. The photoresponse as a function of time was measured by switching the UV light on and off continuously at different forward biases of 1, 3 and 6 V. The results showed that the fabricated UV photodetector has reasonable stability and repeatability. Originality/value This work demonstrated that GaN-based UV photodetector can be fabricated by using the GaN thin film grown by low-cost and simple sol-gel spin coating method.

Transition Metal Complexes with Sulphur Ligands, Part 151 [1]. Ligand Enforced Configurations and Low-Spin States of [FeNS4] Cores in [FeII(L)('pyS4')] Complexes with σ and σ-π Ligands (L = N2H4, pyridine, PMe3, PnPr3; 'pyS4'2- = 2,6-bis(2-mercaptophenylthiomethyl)pyridine (2-))

2001 ◽  
Vol 56 (7) ◽  
pp. 581-588 ◽  
Author(s):  
Dieter Sellmann ◽  
Nicole Blum ◽  
Frank W. Heinemann
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Magnetic Measurements ◽  
Spin States ◽  
X Ray ◽  
Structure Determinations

The reactions of [Fe('pyS4')]2 with PMe3 , PnPr3 , N2H4 and pyridine afforded mononuclear [Fe(L)('pyS4')] complexes with L = PMe3 ( 1 ), PnPr3 (2 ), N2H4 (3) and pyridine (4). NMR spectroscopy, magnetic measurements and X-ray structure determinations revealed that all complexes exhibit frans-thiolate donors and low-spin FeII centres, irrespective of the σ-π or σ ligand character of L. In this regard, the properties of [Fe(L)('pyS4')] complexes strongly contrast with those of [Fe(L)('NHS4')] complexes ('NHS4'2- = 2 ,2 '-bis(2 -mercaptophenylthio)- diethylamine(2 -)) and indicate that the rigid py(CH2)2 entity of the 'pyS42- ligand is able to enforce trans configurations and low-spin states of complexes with [FeNS4 ] cores. In spite of their diamagnetism, confirming the absence of antibonding electrons, all complexes 1 to 4 are highly reactive and rapidly exchange their L ligands for CO to give [Fe(CO)('pyS4')]. Evidence was obtained that the oxidation of [Fe(N'-H4)('pyS4')] (3) yields the diazene complex [μ-N2 H2 {Fe('pyS4’)}2] (5).

Molecular mechanics for multiple spin states of transition metal complexes

2003 ◽  
pp. 3949 ◽  
Author(s):  
Robert J. Deeth ◽  
David L. Foulis ◽  
Benjamin J. Williams-Hubbard
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Molecular Mechanics ◽  
Transition Metal Complexes ◽  
Spin States
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