Theoretical Study of AlnNn, GanNn, and InnNn (n = 4, 5, 6) Clusters

Identification and sensing of hydrogen fluoride (HF) on aluminum phosphide (Al24P24) nanocage in both gas and water phases: electronic study via density-functional theory computations

CONTEXT

Hydrogen fluoride (HF) is extensively present in environmental and industrial pollutants. It may harm the health of humans and animals. This work evaluated the adsorption of an (HF)n linear chain (n = 1, 2, 3, and 4) onto an AlP nanocage through ab initio calculations for the evaluation of its performance in sensing and monitoring (HF)n within aqueous and gaseous media.

METHODS

The present work adopted density functional theory (DFT) at the 6-311 G (d, p) basis set to analyze (HF)n linear chain adsorption onto AlP nanocages with the B3LYP functional. This paper examined the adsorption energy, configuration optimization, work function, and charge transfer. In addition, the contributions of the HF linear chain size to electronic properties and adsorption energy were measured. The dimer form of HF on the surface of AlP nanocages was found to have the highest stability based on the adsorption energy values. Once (HF)n was adsorbed onto the nanocage, the HOMO-LUMO energy gap experienced a large reduction from 3.87 to 3.03 eV, enhancing electrical conductivity. In addition, AlP nanocages may serve in the sensing of (HF)n under multiple environmental pollutants.

Quantum design of transition metals decorated on boron phosphide inorganic nanocluster for Favipiravir adsorption: a possible treatment for COVID-19

Herein, a quantum drug delivery design of transition metals decorated on boron phosphide (B12P12) inorganic nanocage for favipiravir adsorption has been presented. Thus, these systems may facilitate us as COVID-19 therapy.

Prediction of unexpected B n P n structures: promising materials for non-linear optical devices and photocatalytic activities

In the present work, a modern method of crystal structure prediction, namely USPEX conjugated with density functional theory (DFT) calculations, was used to predict the new stable structures of B _n P _n (n = 12, 24) clusters. Since B₁₂N₁₂ and B₂₄N₂₄ fullerenes have been synthesized experimentally, it motivated us to explore the structural prediction of B₁₂P₁₂ and B₂₄P₂₄ clusters. All new structures were predicted to be energetically favorable with negative binding energy in the range from -4.7 to -4.8 eV per atom, suggesting good experimental feasibility for the synthesis of these structures. Our search for the most stable structure of B _n P _n clusters led us to classify the predicted structures into two completely distinct structures such as α-B _n P _n and β-B _n P _n phases. In α-B _n P _n , each phosphorus atom is doped into a boron atom, whereas B atoms form a B _n unit. On the other hand, each boron atom in the β-phase was bonded to a phosphorus atom to make a fullerene-like cage structure. Besides, theoretical simulations determined that α-B _n P _n structures, especially α-B₂₄P₂₄, show superior oxidation resistance and also, both α-B _n P _n and β-B _n P _n exhibit better thermal stability; the upper limit temperature that structures can tolerance is 900 K. The electronic properties of new compounds illustrate a higher degree of absorption in the UV and visible-region with the absorption coefficient larger than 10⁵ cm^-1, which suggests a wide range of opportunities for advanced optoelectronic applications. The β-B _n P _n phase has suitable band alignments in the visible-light excitation region, which will produce enhanced photocatalytic activities. On the other hand, α-B _n P _n structures with modest band gap exhibit large second hyperpolarizability, which are anticipated to have excellent potential as second-order non-linear optical (NLO) materials.

Adsorption of adipic acid in Al/B-N/P nanocages: DFT investigations

Drug delivery clusters based on nanocages recently have been the most capable to study. Adipic acid (ADPA) interaction mechanism over nanocages of X(Al/B)12Y(N/P)12 was investigated. We analyzed various electronic, chemical, and spectroscopic properties with nanocages of the adsorbed ADPA molecule. Adsorption energies were calculated to study the adsorption of ADPA with nanocages. Raman enhanced surface scattering is used to track the drug as an effective approach to vibrational spectroscopy. Detection of the drug has been investigated using the SERS properties of nanocages. Title drug acts as a donor of electrons and adsorbs at the electrophilic site of nanocages. Variations in chemical descriptors to recognize the sensing property of ADPA-nanocages are also noted. Analysis of various properties explains enhancement which makes it possible to detect the drug in other products. • Interaction of adipic acid with fullerene-like metal nanocages • Enhancement of spectral properties • Changes in charge transfer values in nanocage-drug system • Docking studies identify the drug delivery property.

Designing Novel Zn-Decorated Inorganic B12P12 Nanoclusters with Promising Electronic Properties: A Step Forward toward Efficient CO2 Sensing Materials

Gas sensing materials have been widely explored recently owing to their versatile environmental and agriculture monitoring applications. The present study advocates the electronic response of Zn-decorated inorganic B12P12 nanoclusters to CO2 gas. Herein, a series of systems CO2-Zn-B12P12 (E1-E4) are designed by adsorption of CO2 on Zn-decorated B12P12 nanoclusters, and their electronic properties are explored by density functional theory. Initially, placement of Zn on B12P12 delivers four geometries named as D1-D4, with adsorption energy values of -57.12, -22.94, -21.03, and -14.07 kJ/mol, respectively, and CO2 adsorption on a pure B12P12 nanocage delivers one geometry with an adsorption energy of -4.88 kJ/mol. However, the interaction of CO2 with D1-D4 systems confers four geometries named as E1 (E ad = -75.12 kJ/mol), E2 (E ad = -25.89 kJ/mol), E3 (E ad = -42.43 kJ/mol), and E4 (E ad = -28.73 kJ/mol). Various electronic parameters such as dipole moment, molecular electrostatic potential analysis, frontier molecular orbital analysis, Q NBO, global descriptor of reactivity, and density of states are also estimated in order to understand the unique interaction mechanism. The results of these analyses suggested that Zn decoration on B12P12 significantly favors CO2 gas adsorption, and a maximum charge separation is also noted when CO2 is adsorbed on the Zn-B12P12 nanocages. Therefore, the Zn-decorated B12P12 nanocages are considered as potential candidates for application in CO2 sensors.

Adsorption of Phosgene Gas on Pristine and Copper-Decorated B12N12 Nanocages: A Comparative DFT Study

Nanostructured gas sensors find diverse applications in environmental and agricultural monitoring. Herein, adsorption of phosgene (COCl₂) on pure and copper-decorated B₁₂N₁₂ (Cu-BN) is analyzed through density functional theory (DFT) calculations. Adsorption of copper on B₁₂N₁₂ results in two optimized geometries, named Cu@b₆₆ and Cu@b₆₄, with adsorption energies of -193.81 and -198.45 kJ/mol, respectively. The adsorption/interaction energies of COCl₂ on pure BN nanocages are -9.30, -6.90, and -3.70 kJ/mol in G1, G2, and G3 geometries, respectively, whereas the interaction energies of COCl₂ on copper-decorated BN are -1.66 and -16.95 kJ/mol for B1 and B2, respectively. To examine the changes in the properties of pure and Cu-BN nanocages, geometric parameters, dipole moment, Q _NBO, frontier molecular orbitals, and partial density of states (PDOS) are analyzed to comprehensively illustrate the interaction mechanism. The results of these parameters reveal that COCl₂ binds more strongly onto copper-doped BN nanocages. Moreover, a higher charge separation is observed in COCl₂-Cu-BN geometries as compared to copper-decorated BN geometries. Therefore, these nanocages may be considered as potential candidates for application in phosgene sensors.

Zinc-Doped Boron Phosphide Nanocluster as Efficient Sensor for SO2

Adsorption of SO2 on pure B12P12 and Zn-doped B12P12 is investigated through density functional theory methods. Zn adsorption on BP delivers four optimized geometries: B-Top, P-top, b64, and ring-enlarged geometry with adsorption energies of −57.12 kJ/mol, −14.50 kJ/mol, −22.94 kJ/mol, and −14.83 kJ/mol, respectively. The adsorption energy of SO2 on pristine boron phosphide is −14.92 kJ/mol. Interaction of SO2 with Zn-doped boron phosphide gives four different geometries with adsorption energies of −69.76 kJ/mol, −9.82 kJ/mol, −104.92 kJ/mol, and −41.87 kJ/mol. Geometric parameters such as dipole moment, QNBO, frontier molecular orbital analysis, PDOS, and global indices of reactivity are performed to visualize the changes in electronic properties of B12P12 after Zn and SO2 adsorption.

Electronic Structure of Cubane-Like Vanadium–Nitrogen Cationic Clusters [V4N4]+ and [V6N6]+

Density Functional Theory and Complete Active Space Self-Consistent Field (CASSCF) methodologies are used to explore the electronic structure of the cationic V–N clusters, [V4N4]+ and [V6N6]+, that have been identified in recent mass spectrometric experiments. Our calculations indicate that both clusters are based on cubane-like fragments of the rock-salt lattice. In the smaller [V4N4]+ cluster, the V–V bonding is delocalized over the tetrahedron, with net bond orders of 1/3 per V–V bond. In [V6N6]+, in contrast, the V–V bonding is strongly localized in the central V2N2 unit, which has a short V=V double bond. CASSCF calculations reveal that both localized and delocalized V–V bonds are highly multi-configurational.

Comparison of X12Y12 (X=Al, B and Y=N, P) fullerene-like nanoclusters toward adsorption of dimethyl ether

Density functional theory (DFT) was used for studying the adsorption of dimethyl ether (DME) onto four nanoclusters: [Formula: see text] ([Formula: see text], B and [Formula: see text], P). The interaction energy along with the adsorption energy was investigated, and it was found that DME molecule has higher binding energies upon adsorption on Al-containing clusters, but on the other hand, it results in higher alteration in the electronic structure of B-containing cluster. Outcomes of charge analysis and frontier molecular orbital confirm higher alteration in the electronic structure of the later clusters, suggesting the possible potential of B[Formula: see text]N[Formula: see text] and B[Formula: see text]P[Formula: see text] as two sensitive sensors for DME. Nevertheless, Al-containing clusters showed much better adsorbent property, judging from their higher adsorption energies. The positive values of charge transfer upon DME adsorption confirm the p-type semiconducting property of all these clusters.

Carbon dioxide capture by planar (AlN)n clusters (n=3-5)

Searching for materials and technologies of efficient CO₂ capture is of the utmost importance to reduce the CO₂ impact on the environment. Therefore, the (AlN)_n clusters (n = 3-5) are researched using density functional theoretical calculations. The results of the optimization show that the most stable structures of (AlN)_n clusters all display planar configurations at B3LYP and G3B3 methods, which are consistent with the reported results. For these planar clusters, we further systematically studied their interactions with carbon dioxide molecules to understand their adsorption behavior at the B3LYP/6-311+G(d,p) level, including geometric optimization, binding energy, bond index, and electrostatic. We found that the planar structures of (AlN)_n (n = 3-5) can capture 3-5 CO₂ molecules. The result indicates that (AlN)_n (n = 3-5) clusters binding with CO₂ is an exothermic process (the capture of every CO₂ molecule on (AlN)_n clusters releases at least 30 kcal mol^-1 in relative free energy values). These analysis results are expected to further motivate the applications of clusters to be efficient CO₂ capture materials.

DFT simulation towards evaluation the molecular structure and properties of the heterogeneous C16Mg8O8 nano-cage as selective nano-sensor for H2 and N2 gases

Adsorption of hydrogen (H₂) and nitrogen (N₂) molecules was analyzed on a new fullerene-like C₁₆Mg₈O₈ nano-cage, composed of magnesium, oxygen, and carbon, using density functional theory. A detailed analysis of the energy, geometry, and electronic structure of various H₂ and N₂ adsorptions on the cluster surface was performed. The adsorption energies of H₂ and N₂ were estimated to ranging from -0.16 to -0.52eV, respectively. The most stable adsorption configurations were those in which the H or N atoms of the adsorbates were located near the Mg atom of the cluster surface at different sides. It was found that the heterogeneous C₁₆Mg₈O₈ nano-cluster selectively act against the H₂ and N₂ gaseous molecules. The electrical conductivity of the cluster, arising from HOMO/LUMO energy gap, was more sensitive to N₂ gaseous molecule rather than H₂ one, indicating that the heterogeneous C₁₆Mg₈O₈ nano-cage may be potential nano-sensor for N₂ molecule. These findings were specified by analyzing the characteristics in the electron density of states (DOS).

The InN epitaxy via controlling In bilayer

The method of In bilayer pre-deposition and penetrated nitridation had been proposed, which had been proven to have many advantages theoretically. To study the growth behavior of this method experimentally, various pulse times of trimethylindium supply were used to get the optimal indium bilayer controlling by metalorganic vapour phase epitaxy. The results revealed that the InN film quality became better as the thickness of the top indium atomic layers was close to bilayer. A following tuning of nitridation process enhanced the quality of InN film further, which means that a moderate, stable, and slow nitridation process by NH3 flow also plays the key role in growing better-quality InN film. Meanwhile, the biaxial strain of InN film was gradually relaxing when the flatness was increasingly improved.

GEOMETRIES AND ENERGY SEPARATIONS OF ELECTRONIC STATES OF In3N, InN3, AND THEIR IONS

Spectroscopic properties of the low-lying electronic states of In 3 N , InN 3, and their ions are computed by the complete active-space self-consistent field (CASSCF) followed by multireference singles + doubles configuration interaction (MRSDCI) calculations. Our results predict that the spectra of In 3 N / InN 3 are substantially different from those of Ga 3 As / GaAs 3 and Al 3 P / AlP 3 tetramers. The ground state of In 3 N is a closed-shell 1 A ′1 state with a planar D 3h symmetry, whereas the ground state of InN 3 is a 1Σ+ state of linear In – N – N – N structure. The equilibrium geometries, vibrational frequencies, atomization energies, adiabatic ionization potentials, electron affinities, and other properties are discussed.

A comparative study on the B12N12, Al12N12, B12P12 and Al12P12 fullerene-like cages

The stability, geometry and electronic structure of the title nanoclusters were compared by using density functional theory (DFT) calculations. Their electrical property analysis showed that the relative magnitude of the HOMO-LUMO gaps (eV) that are average values from the calculated results with five different DFT functionals is as follows: B12N12(7:02)>>Al12N12(4.09)>B12P12(3.80)>Al12P12(3.39). Computing the standard enthalpy and the Gibbs free energy of formation, it was found that the B(12)N(12) structure is thermodynamically stable at 298 K and 1 atmosphere of pressure, while the Al(12)N(12) structure may be stable at low temperatures. Due to positive values of change of enthalpy and entropy of formation for both the B(12)P(12) and Al(12)P(12) clusters, it seems that their formation from the consisting atoms is not spontaneous at any temperature.

The structural and electronic properties of In(n)N(n = 1-13) clusters

The structural and electronic properties of In(n)N(n=1-13) clusters have been investigated by density-functional theory with the generalized gradient approximation. The results indicate that the equilibrium structures of In(n)N are linear for n=1,2, planar for n=3-5, and three dimensional for n=6-13. Maximum peaks were observed for In(n)N clusters at n=3,7,9 on the size dependence for second-order energy difference. These imply that these clusters possess relatively higher stability, which is consistent with the case of binding energy per atom. Moreover, the results show that the bonding in small In(n)N clusters has a little ionic character by Mulliken population analysis. The energy gap between the highest occupied and lowest unoccupied molecular orbitals, the vertical ionization potential and electron vertical affinity (VIP and VEA) form an even-odd alternating pattern with increasing cluster size. In general, the VIP tends to lower as the cluster size increases, while the VEA tends to increase as the cluster size increases.

Structural, electronic and vibrational properties of small Ga(x)N(y) (x+y = 2-5) nanoclusters: a B3LYP-DFT study

An ab initio study of the stability, structural and electronic properties has been made for 49 gallium nitride nanoclusters, Ga(x)N(y) (x+y = 2-5). Among the various configurations corresponding to a fixed x+y = n value, the configuration possessing the maximum value of binding energy (BE) is named as the most stable structure. The vibrational and optical properties have been investigated only for the most stable structures. A B3LYP-DFT/6-311G(3df) method has been employed to optimize the geometries of the nanoclusters fully. The binding energies (BEs), highest-occupied and lowest-unoccupied molecular orbital (HOMO-LUMO) gaps and the bond lengths have been obtained for all the clusters. We have considered the zero-point energy (ZPE) corrections ignored by the earlier workers. The adiabatic and vertical ionization potentials (IPs) and electron affinities (EAs), charge on atoms, dipole moments, vibrational frequencies, infrared intensities (IR Int.), relative infrared intensities (Rel. IR Int.) and Raman scattering activities have been investigated for the most stable structures. The configurations containing the N atoms in majority are seen to be the most stable structures. The strong N-N bond has an important role in stabilizing the clusters. For clusters containing one Ga atom and all the others as N atoms, the BE increases monotonically with the number of the N atoms. The HOMO-LUMO gap and IP fluctuate with the cluster size n, having larger values for the clusters containing odd number of N atoms. On the other hand, the EA decreases with the cluster size up to n = 3, and shows slow fluctuations thereafter for the larger clusters. In general, the adiabatic IP (EA) is smaller (greater) than the vertical IP (EA) because of the lower energies of the most stable ground state of the cationic (anionic) clusters. The optical absorption spectrum or electron energy loss spectrum (EELS) is unique for every cluster, and may be used to characterize a specific cluster. All the predicted physical quantities are in good agreement with the experimental data wherever available. The growth of these most stable structures should be possible in experiments.

Theoretical study of structure and photoelectron spectroscopy of In(x)P(y)- and In(x)P(y) (x + y < or = 6) clusters

The geometries and vibrational frequencies of In(x)P(y)- and In(x)P(y) are investigated by hybrid B3LYP functional for x + y < or = 6 and CCSD(T) method for x + y < or = 3. As for the small clusters having two to three atoms, the geometrical and electronic structures and vibrational frequencies at the B3LYP level are in good agreement with those at the CCSD(T) level. Among the most stable structures of In(x)P(y)- and In(x)P(y) (x + y < or = 6) clusters the P-rich clusters are more stable than In-rich clusters. Moreover, we found that those P atoms in In(x)P(y)- and In(x)P(y) (x + y < or = 6) clusters prefer to form a P-P bond, triangle, quadrangle, and pentagon for y = 2, 3, 4, and 5, respectively. Also, the vertical detachment energies of In(x)P(y)- (x + y < or = 6) and electron affinities of In(x)P(y) (x + y < or = 6) clusters obtained by B3LYP are in good agreement with the experimental values available. Theoretically, we show that the electron affinity of In3P3 is very low because, as observed in the experiment, there is a formation of a new P-P bond after an electron is lost from In(3)P(3)-, and we find that the similar phenomena exhibit in In2P4(-) cluster as well.

First Principles Study of Neutral and Anionic (Medium-Size) Aluminum Nitride Clusters: AlnNn,n= 7−16

We report the results of a theoretical study of AlnNn (n=7-16) clusters that is based on density functional theory. We will focus on the evolution of structural and electronic properties with the cluster size in the stoichiometric AlN clusters considered. The results reveal that the structural and electronic properties tend to evolve toward their respective bulk limits. The rate of evolution is, however, slow due to the hollow globular shape exhibited by the clusters, which introduces large surface effects that dominate the properties studied. We will also discuss the changes induced upon addition of an extra electron to the respective neutral clusters.

Spectroscopic characterization of the ground and low-lying electronic states of Ga2N via anion photoelectron spectroscopy

Anion photoelectron spectra of Ga(2)N(-) were measured at photodetachment wavelengths of 416 nm(2.978 eV), 355 nm(3.493 eV), and 266 nm(4.661 eV). Both field-free time-of-flight and velocity-map imaging methods were used to collect the data. The field-free time-of-flight data provided better resolution of the features, while the velocity-map-imaging data provided more accurate anisotropy parameters for the peaks. Transitions from the ground electronic state of the anion to two electronic states of the neutral were observed and analyzed with the aid of electronic structure calculations and Franck-Condon simulations. The ground-state band was assigned to a transition between linear ground states of Ga(2)N(-)(X (1)Sigma(g) (+)) and Ga(2)N(X (2)Sigma(u) (+)), yielding the electron affinity of Ga(2)N, 2.506+/-0.008 eV. Vibrationally resolved features in the ground-state band were assigned to symmetric and antisymmetric stretch modes of Ga(2)N, with the latter allowed by vibronic coupling to an excited electronic state. The energy of the observed excited neutral state agrees with that calculated for the A (2)Pi(u) state, but the congested nature of this band in the photoelectron spectrum is more consistent with a transition to a bent neutral state.

Evolution of the Properties of AlnNn Clusters with Size

A global optimization of stoichiometric (AlN)(n) clusters (n = 1-25, 30, 35, ..., 95, 100) has been performed using the basin-hopping (BH) method and describing the interactions with simple and yet realistic interatomic potentials. The results for the smaller isomers agree with those of previous electronic structure calculations, thus validating the present scheme. The lowest-energy isomers found can be classified in three different categories according to their structural motifs: (i) small clusters (n = 2-5), with planar ring structures and 2-fold coordination, (ii) medium clusters (n = 6-40), where a competition between stacked rings and globular-like empty cages exists, and (iii) large clusters (n > 40), large enough to mix different elements of the previous stage. All the atoms in small and medium-sized clusters are in the surface, while large clusters start to display interior atoms. Large clusters display a competition between tetrahedral and octahedral-like features: the former lead to a lower energy interior in the cluster, while the latter allow for surface terminations with a lower energy. All of the properties studied present different regimes according to the above classification. It is of particular interest that the local properties of the interior atoms do converge to the bulk limit. The isomers with n = 6 and 12 are specially stable with respect to the gain or loss of AlN molecules.