scholarly journals Ab-initio simulation of hydrogenated graphene properties

Doklady BGUIR ◽  
2022 ◽  
Vol 19 (8) ◽  
pp. 5-9
Author(s):  
V. V. Murav’ev ◽  
V. M. Mishchenka

Ab-initio simulation of hydrogenated graphene properties was performed. At present, graphene is considered one of the most promising materials for the formation of new semiconductor devices with good characteristics. Graphene has been the subject of many recent investigations due to its peculiar transport, mechanical and others properties [1]. The chemical modification of graphene named as graphane has recently entered the investigation as a possible candidate to solve problems connected with the lack of a graphene bandgap. Graphane is a compound material consisting of two-dimensional graphene bonded by some atoms of hydrogen. The investigation shows that graphane has the three valley Г-М-K band structure with the Г valley, which has the smallest energy gap between the conductivity zone and the valence zone. The calculation of relative electron masses and non-parabolic coefficients in Г, М and K valleys was performed. Based on the obtained characteristics, it is possible to implement a statistical multi-particle Monte Carlo method to determine the characteristics of electron transfer in heterostructure semiconductor devices. A research on modified graphene structures is important for fundamental science and technological applications in high-speed transistor structures operating in the microwave and very high frequency ranges.

2021 ◽  
Vol 13 (3) ◽  
pp. 1505
Author(s):  
Ignacio Menéndez Pidal ◽  
Jose Antonio Mancebo Piqueras ◽  
Eugenio Sanz Pérez ◽  
Clemente Sáenz Sanz

Many of the large number of underground works constructed or under construction in recent years are in unfavorable terrains facing unusual situations and construction conditions. This is the case of the subject under study in this paper: a tunnel excavated in evaporitic rocks that experienced significant karstification problems very quickly over time. As a result of this situation, the causes that may underlie this rapid karstification are investigated and a novel methodology is presented in civil engineering where the use of saturation indices for the different mineral specimens present has been crucial. The drainage of the rock massif of El Regajal (Madrid-Toledo, Spain, in the Madrid-Valencia high-speed train line) was studied and permitted the in-situ study of the hydrogeochemical evolution of water flow in the Miocene evaporitic materials of the Tajo Basin as a full-scale testing laboratory, that are conforms as a whole, a single aquifer. The work provides a novel methodology based on the calculation of activities through the hydrogeochemical study of water samples in different piezometers, estimating the saturation index of different saline materials and the dissolution capacity of the brine, which is surprisingly very high despite the high electrical conductivity. The circulating brine appears unsaturated with respect to thenardite, mirabilite, epsomite, glauberite, and halite. The alteration of the underground flow and the consequent renewal of the water of the aquifer by the infiltration water of rain and irrigation is the cause of the hydrogeochemical imbalance and the modification of the characteristics of the massif. These modifications include very important loss of material by dissolution, altering the resistance of the terrain and the increase of the porosity. Simultaneously, different expansive and recrystallization processes that decrease the porosity of the massif were identified in the present work. The hydrogeochemical study allows the evolution of these phenomena to be followed over time, and this, in turn, may facilitate the implementation of preventive works in civil engineering.


2017 ◽  
Vol 96 (5) ◽  
Author(s):  
Emina Ryuo ◽  
Daisuke Wakabayashi ◽  
Akihide Koura ◽  
Fuyuki Shimojo

2013 ◽  
Vol 2 (1) ◽  
Author(s):  
A. Shamloo ◽  
A.P. Sowa

AbstractWe consider the electronic properties of a system consisting of two quantum dots in physical proximity, which we will refer to as the double-Qdot. Double-Qdots are attractive in light of their potential application to spin-based quantum computing and other electronic applications, e.g. as specialized sensors. Our main goal is to derive the essential properties of the double-Qdot from a model that is rigorous yet numerically tractable, and largely circumvents the complexities of an ab initio simulation. To this end we propose a novel Hamiltonian that captures the dynamics of a bi-partite quantum system, wherein the interaction is described via a Wiener-Hopf type operator. We subsequently describe the density of states function and derive the electronic properties of the underlying system. The analysis seems to capture a plethora of electronic profiles, and reveals the versatility of the proposed framework for double-Qdot channel modelling.


1998 ◽  
Vol 120 (33) ◽  
pp. 8512-8516 ◽  
Author(s):  
Volker Termath ◽  
Frank Haase ◽  
Joachim Sauer ◽  
Jürg Hutter ◽  
Michele Parrinello

1998 ◽  
Vol 94 (21) ◽  
pp. 3229-3235 ◽  
Author(s):  
Armin Klesing ◽  
Detlef Labrenz ◽  
Rutger A. van Santen

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