Topological analysis of steric and relaxation deformation densities

Kheirmand

2023

J. Phys. Chem. A

A model is presented herein for the evaluation of stored charge and energy in molecular-scale capacitors composed of parallel nanosheets. In this model, the nanocapacitor is exposed to an external electric field, and the charging process is considered as a three-stage mechanism, including isolated, exposed, and frozen stages, where each stage possesses its own Hamiltonian and wavefunction. In this way, the third stage’s Hamiltonian is the same as that of the first stage, while its wavefunction is frozen to that of the second stage, and consequently, stored energy can be calculated as the expectation value of second stage’s wavefunction with respect to the first stage’s Hamiltonian. Electron density is then integrated over half-space, i.e., the space separated by a virtual plane located at the middle and parallel to electrodes, to reveal stored charge on nanosheets. The formalism is applied to two parallel hexagonal graphene flakes as nanocapacitor’s electrodes, and results are compared with experimental values of similar systems.

Section: Introductionmentioning

confidence: 99%

Evaluation of Charge and Energy Storage in Molecular Nanocapacitors

Kheirmand

2023

J. Phys. Chem. A

“…Consequently, it is preferred to calculate the layers′ charges independent of atomic charges. On the other hand, deformation density (density difference) analysis has been known as a standard technique to identify inter‐ and intramolecular interactions . Mandado et al have generalized this concept to analyze electric response of molecular wires to external electric field as applied voltage and quantify electron transfer using electron deformation orbitals (EDOs) …”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, deformation density (density difference) analysis has been known as a standard technique to identify inter-and intramolecular interactions. [45][46][47][48][49] Mandado et al have generalized this concept to analyze electric response of molecular wires to external electric field as applied voltage and quantify electron transfer using electron deformation orbitals (EDOs). [45] In the present work, a theoretical study on bilayer graphene in different symmetries, distances and applied voltages is done in the context of EDO theory, the layers' charges as eigenvalues of deformation density matrix are directly calculated, and the overall capacitance of bilayer graphene is estimated.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Prediction of Capacitance of Bilayer Graphene Flakes

Salehi

2020

ChemistrySelect

Electric double layer capacitors (EDLCs) have been known as energy storage device and different materials have been used as EDLC electrode materials. Recently, graphene has been considered as one of the most promising materials for use in EDLC structure. In this research, a theoretical study on bilayer graphene (as an EDLC with vacuum dielectric) in two symmetries (D2h and D6h) with different distances and applied voltages is done, where the charge separation among a bilayer graphene structure is calculated by electron deformation orbital theory. Although it was found that capacitance is almost independent of applied voltage in constant distances, the relationship between capacitance and inverse of distance was nonlinear in the cases of constant voltages. The structure change from D2h to D6h did not affect the specific capacitances, significantly, although the areal capacitance of D2h structure was greater than that of D6h structure.

“…The initial and final states can be originated from different sources, for example, electron attachment and detachment, [22] molecular linear and nonlinear optical responses, [23] Molecular Plasmons, [24] Voronoi deformation density, [25] Hirshfeld charge, [26,27] complex formation, [28,29] electronic excitation, [30] electric field, [31][32][33][34][35] and so on. It has been shown that diagonalization of deformation density matrix bears useful information concerning electron density reorganization due to the process.…”

Section: Introductionmentioning

confidence: 99%

Block deformation analysis: Density matrix blocks as intramolecular deformation density

Ravaei

2020

J Comput Chem

Block deformation analysis as deformation density of atomic orbitals is introduced to analyze intramolecular interactions. In this respect, density matrix blocks in terms of natural atomic orbitals are employed to find interacting and noninteracting multicenter subsystem and extract the corresponding deformation density. Eigenanalysis of this deformation density is performed to result eigenvalues and eigenorbitals as displaced charge due to the intramolecular interaction and orbital space responsible for charge reorganization, respectively, that possesses advantages of other methods, simultaneously. It is applied to several small molecules, different types of carbon allotropes including zero-, one-, and two-dimensional nanostructures, and challenging systems such as ortho-hydrogen atoms in planar biphenyl. Results highly correlate with delocalization and Wiberg bond indices and show that eigenvalues of block deformation analysis deserved to be considered as bonding index.