STRUCTURE AND STABILITY OF ENDOHEDRAL Cn@C60

2010 ◽  
Vol 24 (12) ◽  
pp. 1255-1266 ◽  
Author(s):  
REENA DEVI ◽  
RANJAN KUMAR
Keyword(s):  
Molecular Dynamics ◽  
Charge Transfer ◽  
Free Space ◽  
Chemical Reactivity ◽  
Bond Formation ◽  
Carbon Cluster ◽  
Ab Initio Molecular Dynamics ◽  
Carbon Clusters ◽  
The Stability ◽  
Dynamics Simulations

We report ab initio molecular dynamics simulations of carbon clusters in free space and inside C 60 using SIESTA. We have studied the stability and geometries of small carbon clusters consisting of 2–12 carbon atoms inside the C 60 molecule and in free space by optimizing the atomic geometries. We have found that the C – C bond length is in agreement with the 1.40 and 1.45 values reported earlier. We find that the clusters inside the C 60 are more stable than clusters in free space. Binding energy per carbon atom initially increases with number of carbon atoms in the cluster and then decreases after maximizing for the 9-atom cluster. For more than 9 carbon atoms in the cluster inside C 60, C atoms of the cluster start forming bond with the C 60 cage and the C 60 structure gets distorted. We have done calculations for charge transfer and chemical reactivity. The calculations of ionization potential and electron affinity show that clusters in free space are less reactive compared with C n@ C 60. Charge transfer calculations show that the bond formation of C atoms with the C 60 cage is accompanied with a transfer of charge from carbon cluster to C 60.

Spontaneous Formation and Stability of GaP Cage Structures: A Theoretical Prediction of a New Fullerene

2001 ◽  
Vol 675 ◽  
Author(s):  
Francesco Buda ◽  
Valentina Tozzini ◽  
Annalisa Fasolino
Keyword(s):  
Molecular Dynamics ◽  
Theoretical Prediction ◽  
Ab Initio Molecular Dynamics ◽  
Fullerene Cage ◽  
Spontaneous Formation ◽  
Energy Gaps ◽  
Bulk Structure ◽  
The Stability ◽  
Dynamics Simulations ◽  
Geometric And Electronic Properties

ABSTRACTWe report the spontaneous formation of a GaP fullerene cage in ab-initio Molecular Dynamics simulations starting from a bulk fragment. A systematic study of the geometric and electronic properties of neutral and ionized III-V (GaP, GaAs, AlAs, AIP) clusters suggests the stability of hetero-fullerenes formed by compounds with zincblend bulk structure. Our prediction is supported by several indicators: these clusters show closed electronic shells and relatively large energy gaps; the ratio between the cohesive energy per atom in the cluster and in the bulk is very close to the value found for carbon fullerenes of the same size; the clusters are thermally stable up to a temperature range of 1500–2000 K and they do not dissociate when ionized.

scholarly journals Ab Initio Molecular Dynamics Study of Methanol-Water Mixtures under External Electric Fields

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3371 ◽  
Author(s):  
Giuseppe Cassone ◽  
Adriano Sofia ◽  
Jiri Sponer ◽  
A. Marco Saitta ◽  
Franz Saija
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Electric Fields ◽  
Structural Changes ◽  
Chemical Reactivity ◽  
Pure Water ◽  
Ab Initio Molecular Dynamics ◽  
Sudden Increase ◽  
Molar Ratios ◽  
Dynamics Simulations

Intense electric fields applied on H-bonded systems are able to induce molecular dissociations, proton transfers, and complex chemical reactions. Nevertheless, the effects induced in heterogeneous molecular systems such as methanol-water mixtures are still elusive. Here we report on a series of state-of-the-art ab initio molecular dynamics simulations of liquid methanol-water mixtures at different molar ratios exposed to static electric fields. If, on the one hand, the presence of water increases the proton conductivity of methanol-water mixtures, on the other, it hinders the typical enhancement of the chemical reactivity induced by electric fields. In particular, a sudden increase of the protonic conductivity is recorded when the amount of water exceeds that of methanol in the mixtures, suggesting that important structural changes of the H-bond network occur. By contrast, the field-induced multifaceted chemistry leading to the synthesis of e.g., hydrogen, dimethyl ether, formaldehyde, and methane observed in neat methanol, in 75:25, and equimolar methanol-water mixtures, completely disappears in samples containing an excess of water and in pure water. The presence of water strongly inhibits the chemical reactivity of methanol.

scholarly journals Stability of Calcium Ion Battery Electrolytes: Predictions from Ab Initio Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Sharma Yamijala ◽  
Hyuna Kwon ◽  
Juchen Guo ◽  
Bryan Wong
Keyword(s):  
Molecular Dynamics ◽  
Calcium Ion ◽  
Lithium Ion ◽  
Zinc Ion ◽  
Time Dependent ◽  
Ab Initio Molecular Dynamics ◽  
Elastic Band ◽  
Energy Storage Devices ◽  
The Stability ◽  
Dynamics Simulations

<p>Multivalent batteries, such as magnesium-ion, calcium-ion, and zinc-ion batteries, have attracted significant attention as next-generation electrochemical energy storage devices to complement conventional lithium-ion batteries (LIBs). Among them, calcium-ion batteries (CIBs) are the least explored due to the difficult reversible Ca deposition-dissolution. In this work, we examined the stability of four different Ca salts with weakly coordinating anions and three different solvents commonly employed in existing battery technologies to identify suitable candidates for CIBs. By employing Born-Oppenheimer molecular dynamics (BOMD) simulations on salt-Ca and solvent-Ca interfaces, we find that the tetraglyme solvent and carborane salt are promising candidates for CIBs. Due to the strong reducing nature of the calcium surface, the other salts and solvents readily decompose. We explain the microscopic mechanisms of salt/solvent decomposition on the Ca surface using time-dependent projected density of states, time-dependent charge-transfer plots, and climbing-image nudged elastic band calculations. Collectively, this work presents the first mechanistic assessment of the dynamical stability of candidate salts and solvents on a Ca surface using BOMD simulations, and provides a predictive path toward designing stable electrolytes for CIBs. </p> <p> </p>

scholarly journals Stability of Calcium Ion Battery Electrolytes: Predictions from Ab Initio Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Sharma Yamijala ◽  
Hyuna Kwon ◽  
Juchen Guo ◽  
Bryan Wong
Keyword(s):  
Molecular Dynamics ◽  
Calcium Ion ◽  
Lithium Ion ◽  
Zinc Ion ◽  
Time Dependent ◽  
Ab Initio Molecular Dynamics ◽  
Elastic Band ◽  
Energy Storage Devices ◽  
The Stability ◽  
Dynamics Simulations

<p>Multivalent batteries, such as magnesium-ion, calcium-ion, and zinc-ion batteries, have attracted significant attention as next-generation electrochemical energy storage devices to complement conventional lithium-ion batteries (LIBs). Among them, calcium-ion batteries (CIBs) are the least explored due to the difficult reversible Ca deposition-dissolution. In this work, we examined the stability of four different Ca salts with weakly coordinating anions and three different solvents commonly employed in existing battery technologies to identify suitable candidates for CIBs. By employing Born-Oppenheimer molecular dynamics (BOMD) simulations on salt-Ca and solvent-Ca interfaces, we find that the tetraglyme solvent and carborane salt are promising candidates for CIBs. Due to the strong reducing nature of the calcium surface, the other salts and solvents readily decompose. We explain the microscopic mechanisms of salt/solvent decomposition on the Ca surface using time-dependent projected density of states, time-dependent charge-transfer plots, and climbing-image nudged elastic band calculations. Collectively, this work presents the first mechanistic assessment of the dynamical stability of candidate salts and solvents on a Ca surface using BOMD simulations, and provides a predictive path toward designing stable electrolytes for CIBs. </p> <p> </p>

Impact of vibronic coupling effects on light-driven charge transfer in pyrene-functionalized middle and large-sized Metalloid Gold Nanoclusters from Ehrenfest dynamics.

2021 ◽  
Author(s):  
Adrian Dominguez-Castro ◽  
Thomas Frauenheim
Keyword(s):  
Molecular Dynamics ◽  
Charge Transfer ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Gold Nanoclusters ◽  
Tight Binding ◽  
Time Dependent ◽  
Effective Strategy ◽  
Dynamics Simulations ◽  
Dependent Density

Theoretical calculations are an effective strategy to comple- ment and understand experimental results in atomistic detail. Ehrenfest molecular dynamics simulations based on the real-time time-dependent density functional tight-binding (RT-TDDFTB) approach...

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