Relative stability of Cu, Ag, and Pt at high pressures and temperatures from ab initio calculations

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
N. A. Smirnov
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Relative Stability ◽  
High Pressures ◽  
High Pressures And Temperatures

Phase relations in the Fe-P system at high pressures and temperatures from ab initio computations

2020 ◽  
Vol 40 (2) ◽  
pp. 235-244 ◽  
Author(s):  
Nursultan E. Sagatov ◽  
Pavel N. Gavryushkin ◽  
Maksim V. Banayev ◽  
Talgat M. Inerbaev ◽  
Konstantin D. Litasov
Keyword(s):  
Ab Initio ◽  
High Pressures ◽  
Phase Relations ◽  
P System ◽  
High Pressures And Temperatures ◽  
Ab Initio Computations

scholarly journals Ab initio Determination of the Phase Diagram of CO2 at High Pressures and Temperatures

2020 ◽  
Vol 124 (9) ◽  
Author(s):  
Beatriz H. Cogollo-Olivo ◽  
Sananda Biswas ◽  
Sandro Scandolo ◽  
Javier A. Montoya
Keyword(s):  
Phase Diagram ◽  
Ab Initio ◽  
High Pressures ◽  
High Pressures And Temperatures

scholarly journals Combined Experimental and Theoretical Studies: Lattice-Dynamical Studies at High Pressures with the Help of Ab Initio Calculations

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1283
Author(s):  
Francisco Javier Manjón ◽  
Juan Ángel Sans ◽  
Placida Rodríguez-Hernández ◽  
Alfonso Muñoz
Keyword(s):  
Raman Scattering ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Phase Change Materials ◽  
High Pressures ◽  
Complete Characterization ◽  
Vibrational Properties ◽  
Theoretical Studies ◽  
Experimental And Theoretical Studies

Lattice dynamics studies are important for the proper characterization of materials, since these studies provide information on the structure and chemistry of materials via their vibrational properties. These studies are complementary to structural characterization, usually by means of electron, neutron, or X-ray diffraction measurements. In particular, Raman scattering and infrared absorption measurements are very powerful, and are the most common and easy techniques to obtain information on the vibrational modes at the Brillouin zone center. Unfortunately, many materials, like most minerals, cannot be obtained in a single crystal form, and one cannot play with the different scattering geometries in order to make a complete characterization of the Raman scattering tensor of the material. For this reason, the vibrational properties of many materials, some of them known for millennia, are poorly known even under room conditions. In this paper, we show that, although it seems contradictory, the combination of experimental and theoretical studies, like Raman scattering experiments conducted at high pressure and ab initio calculations, is of great help to obtain information on the vibrational properties of materials at different pressures, including at room pressure. The present paper does not include new experimental or computational results. Its focus is on stressing the importance of combined experimental and computational approaches to understand materials properties. For this purpose, we show examples of materials already studied in different fields, including some hot topic areas such as phase change materials, thermoelectric materials, topological insulators, and new subjects as metavalent bonding.

Ab initio calculations of elastic constants and thermodynamic properties of γTiAl under high pressures

2010 ◽  
Vol 18 (5) ◽  
pp. 761-766 ◽  
Author(s):  
Hongzhi Fu ◽  
Zhiguo Zhao ◽  
WenFang Liu ◽  
Feng Peng ◽  
Tao Gao ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Elastic Constants ◽  
High Pressures

scholarly journals Ab initio calculations of elastic constants of the bcc V–Nb system at high pressures

2006 ◽  
Vol 67 (9-10) ◽  
pp. 2056-2064 ◽  
Author(s):  
A. Landa ◽  
J. Klepeis ◽  
P. Söderlind ◽  
I. Naumov ◽  
O. Velikokhatnyi ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Elastic Constants ◽  
High Pressures

Theoretical studies of azulene and its derivatives

2000 ◽  
Vol 78 (2) ◽  
pp. 224-232 ◽  
Author(s):  
Bo-Cheng Wang ◽  
Yun-Shan Lin ◽  
Jian-Chuang Chang ◽  
Pei-Yu Wang
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Relative Stability ◽  
Basis Set ◽  
Basis Sets ◽  
Ground State Structure ◽  
Geometrical Isomers ◽  
Bromination Product ◽  
Geometry Analysis ◽  
Dft And Mp2 Calculations

The results of ab initio calculations with the 6-31G basis sets on azulene and its derivatives (including azulenequinones and diazoazulenequinones) are presented in accordance with considerations of their structures and bonding. Azulene is a non-alternant compound with ten π electrons and has either a Cs or C2v symmetry depending on the different carbon bonding. The semiempirical and HF ab initio calculations converge to a Cs symmetry and the DFT and MP2 calculations converge to a C2v symmetry as a ground state structure of azulene. The CIS calculations describe the excited state of azulene and the first excitation energy (S0 - S1) is 533 nm (CIS/6-31+G*), which could illustrate the azure color of azulene. According to the geometry analysis, there are 16 geometrical isomers in azulenequinone conjugated diketones of azulene. Ab initio calculation with the 6-31G basis set generates 1,5- and 1,7-azulenequinone being the most stable isomers of azulenequinone. Theoretically, the relative stability of the bromination product of azulenequinones indicates that 7-bromo-1,5-azulenequinone and 3-bromo-1,7- azulenequinone (for monobromoazulenequinones) and 3,7-dibromo-1,5- azulenequinone and 3,5-dibromo-1,7-azulenequinone (for dibromoazulenequinones) are more stable isomers. The product of diazotization of amino- bromoazulenes is diazoazulenequinone in which a diazo group replaces a ketone group. Isomeric 1,8- and 1,2-diazoazulenequinones are the most stable isomers of diazoazulenequinone according to the theoretical consideration. Due to the resonance and relative stability, diazoazulenequinone may easily extrude nitrogen and form the corresponding triplet ketocarbene intermediate and electronic isomers that undergo photoreaction with THF leading to a polyether bridged azulene (crown type ether). The cyclic reactions in diazoazulenequinone are also studied.Key words: azulene, azulenequinone, diazoazulenequinone, ab initio.

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