Synthesis, Characterization, and Density Functional Theory Studies of Three-Dimensional Inorganic Analogues of 9,10-Diboraanthracene—A New Class of Lewis Superacids

2021 ◽  
Author(s):  
Chonghe Zhang ◽  
Junyi Wang ◽  
Wei Su ◽  
Zhenyang Lin ◽  
Qing Ye
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Three Dimensional ◽  
Functional Theory ◽  
New Class

A Density Functional Theory Study of Coniferyl Alcohol Intermonomeric Cross Linkages in Lignin - Three-Dimensional Structures, Stabilities and the Thermodynamic Control Hypothesis

Holzforschung ◽  
2003 ◽  
Vol 57 (2) ◽  
pp. 150-164 ◽  
Author(s):  
B. Durbeej ◽  
L.A. Eriksson
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Structural Features ◽  
Density Functional Theory Study ◽  
Thermodynamic Control ◽  
Functional Theory ◽  
Quantitative Correlation ◽  
Control Hypothesis

Summary Density functional theory methods are utilized to investigate structural features and stabilities of the most common lignin dimerization products. It is found that intra-molecular hydrogen bonding acts as a stabilizing force in the lowest-energy conformer(s) of several different dimeric lignin structures. Furthermore, the calculations show that the hypothesis of thermodynamic control of monolignol dimerization accounts for some of the results obtained in experimental studies aimed at determining the ratios of intermonomeric linkages. A quantitative correlation between experimentally observed ratios and calculated relative energies cannot, however, be pointed out.

An improved scheme for the calculation of NMR chemical shifts in periodic systems based on gauge including atomic orbitals and density functional theory

2011 ◽  
Vol 89 (9) ◽  
pp. 1150-1161 ◽  
Author(s):  
Dmitry Skachkov ◽  
Mykhaylo Krykunov ◽  
Tom Ziegler
Keyword(s):  
Magnetic Field ◽  
Density Functional Theory ◽  
External Magnetic Field ◽  
Density Functional ◽  
Three Dimensional ◽  
Nuclear Magnetic Moment ◽  
Zero Order ◽  
Periodic Systems ◽  
Functional Theory ◽  
Atomic Orbitals

We report here on an improved first principles method that can determine NMR shielding tensors for periodic systems. Our scheme evaluates the shielding tensor as the second derivative of the total electronic energy with respect to a nuclear magnetic moment and an external magnetic field. Both the induced current density J(α) due to the first perturbation from the nuclear magnetic moment as well as the interaction of J(α) with the second perturbation in the form of an external magnetic field are evaluated analytically. Our approach is based on Kohn–Sham density functional theory and gauge-including atomic orbitals. It employs a Bloch basis set made up of Slater-type or numeric atomic orbitals and represents the Kohn–Sham potential fully without the use of effective core potentials. The method is implemented into the periodic program BAND. The new scheme represents an improvement over a previously proposed method in that use can be made of the zero-order Kohn–Sham orbitals from a calculation based on a primitive cell instead of a supercell. Further, J(α) is evaluated analytically rather than by a finite difference approach. The improvements reduce the required computational time by up to two orders of magnitude for three-dimensional systems. Such a reduction is made possible by the fact that we are using atomic centered basis functions. The new implementation is further able to take into account scalar relativistic effects within the zero-order regular approximation. Results from calculations of NMR shielding constants based on the present approach are presented for systems with one-, two-, and three-dimensional periodicity. The reported values are compared to experiment and results from the previously proposed scheme.

scholarly journals A comparative study of AumRhn (4 ≤ m + n ≤ 6) clusters in the gas phase versus those deposited on (100) MgO

2016 ◽  
Vol 18 (32) ◽  
pp. 22122-22128 ◽  
Author(s):  
Fernando Buendía ◽  
Jorge A. Vargas ◽  
Marcela R. Beltrán ◽  
Jack B. A. Davis ◽  
Roy L. Johnston
Keyword(s):  
Genetic Algorithm ◽  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Surface ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Functional Theory ◽  
Phase Versus ◽  
Combined Use

The combined use of a genetic algorithm and Density Functional Theory (DFT) calculations allows us to explore the potential energy surface. Our results show interesting effects on the geometries of the clusters on deposition. Two-dimensional clusters in the gas phase become three-dimensional and vice versa.

Pyridine derivative/graphene nanoribbon composites as molecularly tunable heterogeneous electrocatalysts for the oxygen reduction reaction

2016 ◽  
Vol 18 (6) ◽  
pp. 5040-5047 ◽  
Author(s):  
Huiying Zhang ◽  
Jingxiang Zhao ◽  
Qinghai Cai
Keyword(s):  
Density Functional Theory ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Density Functional ◽  
Reduction Reaction ◽  
Pyridine Derivative ◽  
Functional Theory ◽  
Metal Free ◽  
Dft Computations ◽  
New Class

In this study, a strategy to design a new class of metal-free electrocatalysts for the oxygen reduction reaction (ORR) was proposed by means of density functional theory (DFT) computations.

DENSITY FUNCTIONAL THEORY STUDY OF BINDING ENERGIES, 7Li NUCLEAR MAGNETIC SHIELDING, AND ELECTRIC FIELD GRADIENT TENSORS ON THE SMALL CLUSTERS OF LinHm (m ≤ n ≤ 4)

2007 ◽  
Vol 06 (04) ◽  
pp. 959-973 ◽  
Author(s):  
MEHDI D. ESRAFILI ◽  
FATEMEH ELMI ◽  
NASSER L. HADIPOUR
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Density Functional ◽  
Three Dimensional ◽  
Lithium Hydride ◽  
Binding Energies ◽  
Magnetic Shielding ◽  
Functional Theory

The binding energies, geometries, 7 Li magnetic shielding, and electric field gradient tensors of hydrogenated lithium clusters, Li n H m (m ≤ n ≤ 4), were studied via density functional theory approach. We optimized the structures using B3LYP functional and 6-311++G (2d,2p) basis set. The calculated binding energies of lithium hydride clusters indicate that hydrogenation energy of Li n H m clusters decreases as the number of hydrogen atoms within the cluster increases. Our calculations also showed that for n = 4 clusters, the three-dimensional structure is more stable than the planar one. The study of the trends in the 7 Li magnetic shielding isotropy, σiso, and anisotropies, Δσ, values are explained in terms of the interplay between the electronic and geometrical effects. The variations in the 7 Li nuclear quadrupole coupling constants, χ, and their associated asymmetry parameters, ηQ, for different isomers of the lithium hydride clusters and the influence of hydrogenation on the EFG tensors are also discussed. For n = 4, we obtained a noticeable difference in the χ value from the planar to the three-dimensional structures. The atoms in molecules (AIM) analysis at the Li–H bond critical point reveals remarkably different topographical properties of the charge density and associated Laplacian fields for the planar and three-dimensional lithium hydride clusters.

scholarly journals Electronic and excitonic properties of two-dimensional and bulk InN crystals

RSC Advances ◽  
2017 ◽  
Vol 7 (67) ◽  
pp. 42455-42461 ◽  
Author(s):  
Dan Liang ◽  
Ruge Quhe ◽  
Yingjie Chen ◽  
Liyuan Wu ◽  
Qian Wang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Three Dimensional ◽  
Optoelectronic Properties ◽  
Two Dimensional ◽  
Functional Theory ◽  
Excitonic Properties ◽  
Structural And Optoelectronic Properties

Motivated by potential extensive applications in nanoelectronics devices, we calculate structural and optoelectronic properties of two-dimensional InN as well as its three-dimensional counterparts by using density functional theory.

scholarly journals Communication: Rationale for a new class of double-hybrid approximations in density-functional theory

2011 ◽  
Vol 135 (10) ◽  
pp. 101102 ◽  
Author(s):  
Julien Toulouse ◽  
Kamal Sharkas ◽  
Eric Brémond ◽  
Carlo Adamo
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Functional Theory ◽  
New Class ◽  
Hybrid Approximations
Sign in / Sign up

Export Citation Format

Share Document