Structures and relative stabilities of ammonia clusters at different temperatures: DFT vs. ab initio

2015 ◽  
Vol 17 (43) ◽  
pp. 29226-29242 ◽  
Author(s):  
Alhadji Malloum ◽  
Jean Jules Fifen ◽  
Zoubeida Dhaouadi ◽  
Serge Guy Nana Engo ◽  
Nejm-Eddine Jaidane
Keyword(s):  
Ab Initio ◽  
Global Minimum ◽  
Minimum Energy ◽  
Relative Stabilities ◽  
Different Temperatures ◽  
First Time ◽  
Ammonia Clusters

The global minimum energy structures of (NH3)n=2–10are pointed out for the first time at a given temperature.

Structure and magnetic properties of (Fe2O3)n clusters (n = 1–5)

2014 ◽  
Vol 16 (48) ◽  
pp. 26421-26426 ◽  
Author(s):  
A. Erlebach ◽  
C. Hühn ◽  
R. Jana ◽  
M. Sierka
Keyword(s):  
Magnetic Properties ◽  
Global Minimum ◽  
Size Range ◽  
Weak Dependence ◽  
Relative Stabilities ◽  
Magnetic States ◽  
First Time

Global minimum structures of (Fe2O3)n clusters (n = 1–5) determined for the first time in this size range show weak dependence of the structure and relative stabilities of different isomers on their magnetic states.

scholarly journals Ab initio studies of structural, electronic, optical, elastic and thermal properties of CuGaTe-=SUB=-2-=/SUB=-

2017 ◽  
Vol 51 (5) ◽  
pp. 711
Author(s):  
Pravesh Singh ◽  
Sheetal Sharma ◽  
Sarita Kumari ◽  
Vibhav K Saraswat ◽  
D. Sharma ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Structural Parameters ◽  
Debye Model ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
Different Temperatures ◽  
First Time ◽  
Linearized Augmented Plane Wave

We have performed ab initio calculations for the structural, electronic, optical, elastic and thermal properties of CuGaTe2. In this study, we used an accurate full potential linearized augmented plane wave (FP-LAPW) method to find the equilibrium structural parameters and to compute the full elastic tensors. We report electronic and optical properties with the recently developed density functional of Tran and Blaha. Furthermore, optical features such as dielectric functions, refractive indices, extinction coefficient, optical reflectivity, absorption coefficients, optical conductivities, were calculated for photon energies up to 30 eV. The thermodynamical properties such as Debye temperature, entropy and Gruneisen parameter, bulk modulus and hardness were calculated employing the quasi-harmonic Debye model at different temperatures (0-1000 K) and pressures (0-8 GPa) and the silent results were interpreted. Most of the investigated parameters are reported for the first time. DOI: 10.21883/FTP.2017.05.44433.8044

THE ϕ, ψ SPACE OF BORON ISOSTERES OF AMINO ACIDS: AN AB INITIO STUDY

2004 ◽  
Vol 03 (02) ◽  
pp. 189-202 ◽  
Author(s):  
P. A. DATAR ◽  
E. C. COUTINHO
Keyword(s):  
Amino Acids ◽  
Ab Initio ◽  
Global Minimum ◽  
Molecular Electrostatic Potential ◽  
Enzyme Inhibitor ◽  
Minimum Energy ◽  
Positive Potential ◽  
Atomic Size ◽  
Normal Enzyme ◽  
Natural Amino Acids

Boron isosteres [ CH 3- CO - BH - CH(R) - CONHCH 3; R = CH 3, CH 2 OH , CH 2 SH ] of natural amino acids have been designed as inhibitors of serine protease based on boron's ability to mimic the transition state of the normal enzyme catalyzed reaction. The conformation and electronic properties of these isosteres have been determined by ab initio calculations at the HF/6-31G** level of theory. The global minimum energy structures of the boron isosteres (which are all identical) and the natural amino acids are radically different. Interestingly, the boron isosteres have favorable conformations with positive values for the ϕ dihedral, which are "disallowed states" for the natural amino acids. This is possible because of the smaller atomic size of boron compared to nitrogen. The molecular electrostatic potential of the boron isosteres is also very different from the natural amino acids. There is a positive potential around the boron atom, which provokes the attack of the Ser 195– OH group in the enzyme, resulting in formation of an irreversible enzyme-inhibitor adduct.

scholarly journals Approaching Bulk from the Nanoscale: Extrapolation of Binding Energy from Rock-Salt Cuts of Alkaline Earth Metal Oxides

2021 ◽  
Vol 74 ◽  
Author(s):  
Susanne G.E.T. Escher ◽  
Helen D. Duncan ◽  
Alexey A. Sokol ◽  
Scott M. Woodley
Keyword(s):  
Metal Oxides ◽  
Rock Salt ◽  
Alkaline Earth ◽  
Global Minimum ◽  
Minimum Energy ◽  
Earth Metal ◽  
Alkaline Earth Metal ◽  
Bulk Rock ◽  
Alkaline Earth Metal Oxides ◽  
The Stability

ABSTRACT A systematic DFT study is performed on (MgO)B, (CaO)n, (SrO)n, and (BaO)n clusters with 6 < n < 50, and which display a cuboid 2X2X2 atomic motif seen in the bulk, rock-salt, configuration. The stability and energy progression of these clusters are used to predict the energies of infinitely long nanorods, or nanowires, slabs, and the bulk global minimum energy. Keywords: Alkaline earth metal oxides, nanoclusters, nanorods, DFT.

scholarly journals Identification of mechanical damage in the 'Fuji' apple cv. using artificial hyperspectral vision

DYNA ◽  
2019 ◽  
Vol 86 (210) ◽  
pp. 224-232
Author(s):  
Oscar Leonardo García Navarrete ◽  
Sergio Cubero García ◽  
José Manuel Prats Montalbán
Keyword(s):  
Discriminant Analysis ◽  
Impact Damage ◽  
Mechanical Damage ◽  
Hyperspectral Images ◽  
Different Temperatures ◽  
Fuji Apple ◽  
First Time ◽  
Sampling Times ◽  
Over Time

One problem in the post-harvest phase of apples is the mechanical impact damage; its identification prevents quality issues during storage. The objective was to identify the wavelengths at which the damage is detected early in apples of the 'Fuji' cultivar, simulating the damage with a controlled stroke and taking hyperspectral images from 400 to 1700 nm. Three experiments were carried out at different temperatures (4 and 20 ° C) and with varying sampling times. It was found that in the NIR zone ranging between 1050 and 1100 nm, it was possible to classify healthy and bruised zones by means of a discriminant analysis by partial least squares (PLS-DA). Additionally, the evolution of the damage over time was not significant for the classification of the pixels (healthy and bruised classes), since bumps were detected in all three experiments from the first time.

scholarly journals An ab initio Hartree-Fock Investigation of Endohedral Sc@C82

1998 ◽  
Vol 53 (9) ◽  
pp. 801-805 ◽  
Author(s):  
Andrea Gruß ◽  
Michael C. Böhm ◽  
Joachim Schulte ◽  
Klaus-Peter Dinse
Keyword(s):  
Ab Initio ◽  
Minimum Energy ◽  
Fullerene Cage ◽  
Site Symmetry ◽  
Fold Axis ◽  
Hartree Fock ◽  
Endohedral Complex ◽  
Experimental Findings ◽  
Ab Initio Hf ◽  
Hf Calculations

Abstract The electronic structure of endohedral Sc@C82 with a C82 cage of C2v symmetry has been studied by ab initio Hartree-Fock (HF) calculations. The optimized position of Sc in the configuration of minimum energy is predicted to be on the two-fold axis of the fullerene cage. In the corresponding configuration Sc is above the center of a hexagon of site symmetry C2 . This structure of C2v symmetry is nearly degenerate with Cs and Ct structures with Sc slightly displaced from the center of the coordinated hexagon. The binding energy of the endohedral complex is larger than 3.55 eV. The ab initio HF data of the C2v topoisomer of the fullerene unit are compared with new experimental findings and HF results derived for the 3(C2) topoisomer of the C82 cage.

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