scholarly journals A Chirality Chain in Phenylglycine, Phenylpropionic Acid, and Ibuprofen

Symmetry ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 55
Author(s):  
Henri Brunner ◽  
Takashi Tsuno ◽  
Gábor Balázs
Keyword(s):  
Amino Acids ◽  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Carboxylic Group ◽  
Natural Amino Acid ◽  
Functional Theory ◽  
Structural Pattern ◽  
Phenylpropionic Acid ◽  
Natural Amino Acids

Our strategy to analyze the structures of natural amino acids with respect to the interaction of three different elements of chirality within the molecules was applied to the non-natural amino acid (S)-α-phenylglycine, its analogue (S)-α-phenylpropionic acid, and the drug (S)-ibuprofen. The three chirality elements are the configuration at Cα, the conformation at the Cα-C’ bond, and the distortion of the planar carboxylic group to a flat asymmetric tetrahedron. In all three compounds, a given (S) configuration at Cα predominantly induces (M) conformation at the Cα-C’ bond, which in turn preferentially distorts the carboxylic group to a tetrahedron with (R) configuration. Both steps of this chirality chain display high selectivities. Due to varying co-crystallization partners, in all the structures the molecules are in different environments with respect to packing and hydrogen bonding. Nevertheless, the structural pattern and the diaselectivities of the chirality chain persist. For phenylglycine, DFT (Density Functional Theory) calculations confirm the structural results.

scholarly journals Confirmation of Initial Stable Adsorption Structures of Leucine and Tyrosine Adsorbed on a Cu(110) Surface

2020 ◽  
Vol 10 (4) ◽  
pp. 1284
Author(s):  
Hangil Lee ◽  
Hyun Sung Kim
Keyword(s):  
Amino Acids ◽  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Photoemission Spectroscopy ◽  
Functional Theory ◽  
Reflection Absorption Infrared Spectroscopy ◽  
Carboxylic Groups ◽  
Favorable Structure ◽  
Initial Coverage

The structures and stability levels of leucine (Leu) and tyrosine (Tyr) adsorbed on a Cu(110) surface, at initial levels of coverage (less than 0.25 monolayer), were investigated using reflection–absorption infrared spectroscopy and high-resolution photoemission spectroscopy (HRPES), as well as by performing density functional theory calculations. At an initial coverage, the O–H dissociation bonded structure was indicated from the spectral results to be the most favorable structure for Leu adsorbed on the Cu(110) surface, whereas the O–H dissociated-N dative bonded structure was most favorable for adsorbed Tyr. These models were further supported by the results of experiments, in which the systems were exposed to other molecules and HRPES was used to monitor whether the amine or carboxylic groups of the adsorbed amino acids became reactive.

Is a Non-Transition Element Nitride Ferromagnet Ever Achievable? Indication of the N-N Pairing Instability

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1525-1531 ◽  
Author(s):  
Wojciech Grochala
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Transition Element ◽  
Density Functional Theory Calculations ◽  
Functional Theory

The enthalpy of four polymorphs of CaN has been scrutinized at 0 and 100 GPa using density functional theory calculations. It is shown that structures of diamagnetic calcium diazenide (Ca2N2) are preferred over the cubic ferromagnetic polymorph (CaN) postulated before, both at 0 and 100 GPa.

scholarly journals Tensor-structured algorithm for reduced-order scaling large-scale Kohn–Sham density functional theory calculations

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Chih-Chuen Lin ◽  
Phani Motamarri ◽  
Vikram Gavini
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Density Functional Theory Calculations ◽  
System Size ◽  
Real Space ◽  
Functional Theory ◽  
Reduced Order ◽  
Separable Approximation ◽  
Tensor Basis

AbstractWe present a tensor-structured algorithm for efficient large-scale density functional theory (DFT) calculations by constructing a Tucker tensor basis that is adapted to the Kohn–Sham Hamiltonian and localized in real-space. The proposed approach uses an additive separable approximation to the Kohn–Sham Hamiltonian and an L1 localization technique to generate the 1-D localized functions that constitute the Tucker tensor basis. Numerical results show that the resulting Tucker tensor basis exhibits exponential convergence in the ground-state energy with increasing Tucker rank. Further, the proposed tensor-structured algorithm demonstrated sub-quadratic scaling with system-size for both systems with and without a gap, and involving many thousands of atoms. This reduced-order scaling has also resulted in the proposed approach outperforming plane-wave DFT implementation for systems beyond 2000 electrons.

scholarly journals Polymorphs of Rb3ScF6: X-ray and Neutron Diffraction, Solid-State NMR, and Density Functional Theory Calculations Study

2021 ◽  
Vol 60 (8) ◽  
pp. 6016-6026
Author(s):  
Aydar Rakhmatullin ◽  
Maxim S. Molokeev ◽  
Graham King ◽  
Ilya B. Polovov ◽  
Konstantin V. Maksimtsev ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Neutron Diffraction ◽  
Solid State Nmr ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
X Ray

Graphene adlayer growth between nonepitaxial graphene and Ni(111) substrate: a promising theoretical scheme

2020 ◽  
Author(s):  
Lijuan Meng ◽  
Jinlian Lu ◽  
Yujie Bai ◽  
Lili Liu ◽  
Tang Jingyi ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Chemical Vapor Deposition ◽  
Molecular Dynamics Simulations ◽  
Vapor Deposition ◽  
Density Functional ◽  
Chemical Vapor ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Dynamics Simulations

Understanding the fundamentals of chemical vapor deposition bilayer graphene growth is crucial for its synthesis. By employing density functional theory calculations and classical molecular dynamics simulations, we have investigated the...

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