The Energetics of Hydrogen Adsorbed in Nanoporous Silicon. An ab initio Simulational Study

2006 ◽  
Vol 971 ◽  
Author(s):  
Ariel A. Valladares ◽  
Alexander Valladares ◽  
R. M. Valladares ◽  
A. G. Calles
Keyword(s):  
Porous Silicon ◽  
Total Energy ◽  
Ab Initio ◽  
Average Energy ◽  
Dangling Bonds ◽  
Bond Energies ◽  
Hydrogen Atoms ◽  
Nanoporous Silicon ◽  
Pure Silicon ◽  
Interesting Alternative

ABSTRACTPorous silicon may be an interesting alternative to store hydrogen. Unlike carbon, its bonding multiplicity is limited, and because of this, the probability of having more dangling bonds on the pore surface is larger than in carbon. Using nanoporous silicon periodic supercells with 216 atoms and 50 % porosity, constructed with a novel ab initio approach devised by us, the dangling bonds of the silicon atoms were first saturated with hydrogen, then relaxed and its total energy calculated. Next the same number of hydrogen atoms was placed within the pore in the pure silicon supercell, then the sample relaxed, and finally its total energy calculated, with and without hydrogens. From these results the average energy per hydrogen atom is obtained. We compare our results to SiH bond energies and to previous results for hydrogenated carbon; conclusions are drawn concerning the possibility of using porous silicon as a fuel tank for hydrogen.

Hydrogen adsorbed in ab initio computationally simulated nanoporous carbon. An energetics study

2007 ◽  
Vol 1042 ◽  
Author(s):  
R. M. Valladares ◽  
Alexander Valladares ◽  
A. G. Calles ◽  
Ariel A. Valladares
Keyword(s):  
Hydrogen Atom ◽  
Binding Energy ◽  
Total Energy ◽  
Ab Initio ◽  
Molecular Hydrogen ◽  
Molecular Form ◽  
Average Energy ◽  
Nanoporous Carbon ◽  
Hydrogen Atoms ◽  
Pure Carbon

AbstractNanoporous carbon has been considered an interesting and potentially useful material for storing hydrogen. Using nanoporous carbon periodic supercells with 216 atoms and 50 % porosity, constructed with a novel ab initio approach devised by us, the dangling bonds of the carbon atoms were first saturated with hydrogen, then relaxed and its total energy calculated with and without hydrogen. Next the same number of hydrogen atoms, in molecular form, was randomly placed within the pore of the pure carbon supercell, then the sample relaxed, and finally its total energy calculated, also with and without hydrogens. From these results the average energy per hydrogen atom is obtained for both cases. For the molecular hydrogen sample the binding energy found per hydrogen atom is 343.89 meV, which compares favourably with values reported in the literature, 300-400 meV/molecule.

Formation of surface layer of hydrogen in pure aluminum

2019 ◽  
Vol 484 (1) ◽  
pp. 56-60
Author(s):  
D. A. Indejtsev ◽  
E. V. Osipova
Keyword(s):  
Surface Layer ◽  
Hydrogen Atom ◽  
Ab Initio ◽  
Pure Aluminum ◽  
Hydrogen Atoms ◽  
Energy Characteristics ◽  
Aluminum Crystal

Hydrogen atom behavior in pure aluminum is described by ab initio modelling. All main energy characteristics of the system consisting of hydrogen atoms in a periodic aluminum crystal are found.

Effect of Chromium and Vanadium on Nanolayered Ternary Carbides: AB Initio Study

2009 ◽  
Vol 609 ◽  
pp. 239-242
Author(s):  
A.E. Merad ◽  
M.B. Kanoun
Keyword(s):  
Electronic Structure ◽  
Total Energy ◽  
Ab Initio ◽  
Structural Parameters ◽  
Ab Initio Study ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Full Relaxation ◽  
Relaxation Procedure ◽  
Ternary Carbides

The Cr2AlC and V2AlC nanolayered ternary carbides are studied by performing APW-lo ab initio total energy calculations within the recent Wu-Cohen generalized gradient approximation GGA. Using full relaxation procedure of the volume and the atomic positions we obtained the structural parameters and electronic structure of the optimization hexagonal. Results were compared with the experimental ones. Interesting features are deduced. In fact, we have shown why these materials are conductors.

Ab Initio Determination of a New Complex Structure (55 Non-Hydrogen Atoms) from Synchrotron Powder Data: An Uncommon Nickel Succinate, Ni7(C4H4O4)4(OH)6(H2O)3•7H2O

2004 ◽  
Vol 443-444 ◽  
pp. 333-336
Author(s):  
N. Guillou ◽  
C. Livage ◽  
W. van Beek ◽  
G. Férey
Keyword(s):  
Ab Initio ◽  
Complex Structure ◽  
Three Dimensional ◽  
Free Water ◽  
Hydrogen Atoms ◽  
Monoclinic System ◽  
Synchrotron Powder Diffraction ◽  
Chloride Hexahydrate ◽  
Autogenous Pressure

Ni7(C4H4O4)4(OH)6(H2O)3. 7H2O, a new layered nickel(II) succinate, was prepared hydrothermally (180°C, 48 h, autogenous pressure) from a 1:1.5:4.1:120 mixture of nickel (II) chloride hexahydrate, succinic acid, potassium hydroxide and water. It crystallizes in the monoclinic system (space group P21/c, Z = 4) with the following parameters a = 7.8597(1) Å, b = 18.8154(3)Å, c = 23.4377(4) Å,ϐ = 92.0288(9)°, and V = 3463.9(2) Å3. Its structure, which contains 55 non-hydrogen atoms, was solved ab initio from synchrotron powder diffraction data. It can be described from hybrid organic-inorganic layers, constructed from nickel oxide corrugated chains. These chains are built up from NiO6hexameric units connected via a seventh octahedron. Half of the succinates decorate the chains, and the others connect them to form the layers. The three dimensional arrangement is ensured by hydrogen bonds directly between two adjacent layers and via free water molecules.

Contributions to Silicon-Hydrogen Bond-Stretching Frequency in Amorphous Si Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
Z. Jing ◽  
J. L. Whitten ◽  
G. Lucovsky
Keyword(s):  
Experimental Data ◽  
Hydrogen Bond ◽  
Dielectric Constant ◽  
Ab Initio ◽  
Effective Dielectric Constant ◽  
Bond Energies ◽  
Calculated Frequency ◽  
Bond Stretching ◽  
Amorphous Si ◽  
Good Agreement

ABSTRACTWe have performed ab initio calculations and determined the bond-energies and vibrational frequencies of Si-H groups that are: i) attached to Si-atoms as their immediate, and also more distant neighbors; and ii) attached to three O-atoms as their immediate neighbors, but are connected to an all Si-atom matrix. These arrangements simulate bonding geometries on Si surfaces, and the calculated frequency for i) is in good agreement with that of an Si-H group on an Si surface. To compare these results with a-Si:H alloys it is necessary to take into account an additional factor: the effective dielectric constant of the host. We show how to do this, demonstrating the way results of the ab initio calculations should then be compared with experimental data.

Hydrogenated Amorphous Silicon Nitride: Structural and Electronic Properties

1998 ◽  
Vol 538 ◽  
Author(s):  
J. F. Justo ◽  
F. De Brito Mota ◽  
A. Fazziom
Keyword(s):  
Silicon Nitride ◽  
Ab Initio ◽  
Amorphous Silicon ◽  
Electronic Properties ◽  
Interatomic Potential ◽  
Hydrogen Atoms ◽  
Hydrogen Incorporation ◽  
Amorphous Silicon Nitride ◽  
Structural And Electronic Properties ◽  
Hydrogenated Amorphous

AbstractWe combined empirical and ab initio methods to study structural and electronic properties of amorphous silicon nitride. For such study, we developed an interatomic potential to describe the interactions between silicon, nitrogen, and hydrogen atoms. Using this potential, we performed Monte Carlo simulations in a simulated annealing scheme to study structural properties of amorphous silicon nitride. Then this potential was used to generate relevant structures of a-SiNx:Hy which were input configurations to ab initio calculations. We investigated the electronic and structural role played by hydrogen incorporation in amorphous silicon nitride.

scholarly journals Toward fully quantum modelling of ultrafast photodissociation imaging experiments. Treating tunnelling in the ab initio multiple cloning approach

2016 ◽  
Vol 194 ◽  
pp. 81-94 ◽  
Author(s):  
Dmitry V. Makhov ◽  
Todd J. Martinez ◽  
Dmitrii V. Shalashilin
Keyword(s):  
Kinetic Energy ◽  
Ab Initio ◽  
Energy Release ◽  
Kinetic Energy Release ◽  
Total Kinetic Energy ◽  
Recent Effort ◽  
Experimental Measurements ◽  
Quantum Level ◽  
Hydrogen Atoms ◽  
Quantum Simulations

We present an account of our recent effort to improve simulation of the photodissociation of small heteroaromatic molecules using the Ab Initio Multiple Cloning (AIMC) algorithm. The ultimate goal is to create a quantitative and converged technique for fully quantum simulations which treats both electrons and nuclei on a fully quantum level. We calculate and analyse the total kinetic energy release (TKER) spectra and Velocity Map Images (VMI), and compare the results directly with experimental measurements. In this work, we perform new extensive calculations using an improved AIMC algorithm that now takes into account the tunnelling of hydrogen atoms. This can play an extremely important role in photodissociation dynamics.

Hydrogen Storage in MgH2 Matrices: An Ab-Initio Study of Mg-MgH2 Interface

2008 ◽  
Vol 139 ◽  
pp. 23-28 ◽  
Author(s):  
Simone Giusepponi ◽  
Massimo Celino ◽  
Fabrizio Cleri ◽  
Amelia Montone
Keyword(s):  
Molecular Dynamics ◽  
Total Energy ◽  
Ab Initio ◽  
Atomic Hydrogen ◽  
Level Structure ◽  
Atomic Level ◽  
Work Of Adhesion ◽  
Ab Initio Study ◽  
Dynamics Method ◽  
Good Agreement

We studied the atomic-level structure of a model Mg-MgH2 interface by means of the Car-Parrinello molecular dynamics method (CPMD). The interface was characterized in terms of total energy calculations, and an estimate of the work of adhesion was given, in good agreement with experimental results on similar systems. Furthermore, the interface was studied in a range of temperatures of interest for the desorption of hydrogen. We determined the diffusivity of atomic hydrogen as a function of the temperature, and give an estimate of the desorption temperature.

scholarly journals The ‘Inverted Bond’ revisited. Analysis of ‘in silico’ models and of [1.1.1]Propellane using Orbital Forces

2019 ◽  
Author(s):  
Rubén Laplaza ◽  
Julia Contreras-García ◽  
Franck Fuster ◽  
François Volatron ◽  
Patrick Chaquin
Keyword(s):  
Total Energy ◽  
Molecular Orbital ◽  
In Silico ◽  
Bond Energies ◽  
Parent Molecule ◽  
Ca 50 ◽  
In Silico Models ◽  
Mo Theory

<div>This article dwells on the nature of “inverted bonds”, which make reference to the σ interaction between two s-p hybrids by their smaller lobes, and their presence in [1.1.1]propellane <b>1</b>. Firstly we study H 3 C-C models of C-C bonds with frozen HCC angles reproducing the constraints of various degrees of “inversion”. Secondly, the molecular orbital (MO) properties of [1.1.1]propellane <b>1</b> and [1.1.1]bicyclopentane <b>2</b> are analyzed with the help of orbital forces as a criterion of bonding/antibonding character and as a basis to evaluate bond energies. Triplet and cationic state of <b>1</b> species are also considered to confirm the bonding/antibonding character of MOs in the parent molecule. These approaches show an essentially non-bonding character of the σ central CC interaction in propellane. Within MO theory, this bonding is thus only due to π-type MOs (also called ‘banana’ MOs or ‘bridge’ MOs) and its total energy is evaluated to ca. 50 kcal/mol. In bicyclopentane <b>2</b>, despite a strong σ-type repulsion, a weak bonding (15-20 kcal/mol) exists between both central CC, also due to π-type interactions, though no bond is present in the Lewis structure. Overall, the so-called ‘inverted’ bond, as resulting from a σ overlap of the two s-p hybrids by their smaller lobes, appears highly questionable.</div>

Sign in / Sign up

Export Citation Format

Share Document