Microenvironment and electronic state modulation of Pd nanoparticles within MOFs for enhancing low-temperature activity towards DCPD hydrogenation

Precise control of the local environment and electronic state of the guest is an important method of controlling catalytic activity and reaction pathways.In this paper,guest Pd NPs were introduced into a series of host UiO-67 MOFs with different functional ligands and metal nodes,the microenvironment and local electronic structure of Pd is modulated by introducing bipyridine groups and changing metal nodes(Ce_(6)O_(6) or Zr_(6)O_(6)).The bipyridine groups not only promoted the dispersion Pd NPs,but also facilitated electron transfer between Pd and UiO-67 MOFs through the formation of Pd-N bridges.Compared with Zr6 clusters,the tunability and orbital hybridisation of the 4f electronic structure in the Ce_(6) clusters modulate the electronic structure of Pd through the construction of the Ce-O-Pd interfaces.The optimal catalyst Pd/UiO-67(Ce)-bpy presented excellent low-temperature activity towards dicyclopentadiene hydrogenation with a conversion of>99% and a selectivity of>99%(50℃,10 bar).The results show that the synergy of Ce-O-Pd and Pd-N promotes the formation of active Pd^(δ+),which not only enhances the adsorption of H_(2) and electron-rich C=C bonds,but also contributes to the reduction of proton migration distance and improves proton utilization efficiency.These results provide valuable insights for investigating the regulatory role of the host MOFs,the nature of host-guest interactions,and their correlation with catalytic performance.

Optical spectroscopy of CrO and electronic states of the Cr group metal monoxides

All of the experimentally known electronic states of the Cr group metal monoxides(Cr O,Mo O,and WO)have been presented in the paper.The optical spectra of the Cr O molecule have been investigated in the gas phase through a combination of the laser-induced fluorescence(LIF)excitation and single-vibronic-level(SVL)emission spectroscopy in the supersonic expansion.The rotational constants of the vibronic electronic states,including X^(5)Π_(-1)(v=0–3),B^(5)Π_(-1)(v=0–10),and B~5Π_1(v=1,5),and the vibrational constants of the spin–orbit components X^(5)Π_(-1,0,1)have been obtained.The molecular constants of the Mo O and WO molecules have been summarized by reviewing the previous spectroscopic studies,and a comprehensive energy level diagram of the Cr group metal monoxides has been constructed.By comparing the electronic configurations,bond lengths,and vibrational frequencies of all the transition metal monoxides in the ground electronic state,the significance of the relativistic effect in the bonding of the 5d transition metal monoxides has been discussed.The related spectroscopic data of the Cr O molecule are available at https://doi.org/10.57760/sciencedb.j00113.00085.

Electronic States of a Shallow Hydrogenic Donor Impurity in Different Shaped Semiconductor Quantum Wells

The shallow hydrogenic donor impurity states in square, V-shaped, and parabolic quantum wells are studied in the framework of effective-mass envelope-function theory using the plane wave basis. The first four impurity energy levels and binding energy of the ground state are more easily calculated than with the variation method. The calculation results indicate that impurity energy levels decrease with the increase of the well width and decrease quickly when the well width is small. The binding energy of the ground state increases until it reaches a maximum value, and then decreases as the well width increases. The results are meaningful and can be widely applied in the design of various optoelectronie devices.

Atomic insights of electronic states engineering of GaN nanowires by Cu cation substitution for highly efficient lithium ion battery

Electronic engineering of gallium nitride(Ga N) is critical for enhancement of its electrode performance.In this work, copper(Cu) cation substituted Ga N(Cu-Ga N) nanowires were fabricated to understand the electronically engineered electrochemical performance for Li ion storage. Cu cation substitution was revealed at atomic level by combination of X-ray photoelectron spectroscopy(XPS), X-ray absorption fine structure(XAFS), density functional theory(DFT) simulation, and so forth. The Cu-Ga N electrode delivered high capacity of 813.2 m A h g^(-1) at 0.1 A g^(-1) after 200 cycles, increased by 66% relative to the unsubstituted Ga N electrode. After 2000 cycles at 10 A g^(-1),the reversible capacity was still maintained at326.7 m A h g^(-1). The DFT calculations revealed that Cu substitution introduced the impurity electronic states and efficient interatomic electron migration, which can enhance the charge transfer efficiency and reduce the Li ion adsorption energy on the Cu-Ga N electrode. The ex-situ SEM, TEM, HRTEM, and SAED analyses demonstrated the reversible intercalation Li ion storage mechanism and good structural stability. The concept of atomic-arrangement-assisted electronic engineering strategy is anticipated to open up opportunities for advanced energy storage applications.

Electronic States of Difluorocarbene Calculated by Multireference Configuration Interaction Method

We investigate the geometries and energies of seven electronic states X-1A1, A1B1, a-3B1, B-1A2,b-3A2, C1B2 and c-3B2 of CF2 carbene using internally contracted multireference configuration interaction methods including Davidson correction （icMRCIq-Q） with different basis sets aug-cc-pVXZ （X=T, Q, 5）. For the first time, the potential energy curves of electronic states of CF2 related icMRCI＋Q/aug-cc-pVTZ level. The ab initio results will and dynamics of electronic states of CF2 radical. to the lowest dissociation limit are calculated at the further increase our understanding of the structures

Effect of Ultrasonication on Optical Properties and Electronic States of Conjugated Polymer MEH-PPV

Poly[2-methoxy-5-（2＇-ethyl-hexyloxy）-1,4-phenylene vinylene]（MEH-PPV）solutions with different concen-trations were prepared in chloroform for different ultrasonication times.The ultraviolet absorption and photoluminescence（PL）spectra of the MEH-PPV solutions were measured,and the electronic states of the polymer chains under different experimental conditions were studied.The results showed that the effects of ultrasonication on the dilute and concentrated solutions were different.After ultrasonication,the intensity of the absorption peak at 280 nm significantly decreased,relative to the absorption peak at 500 nm for both dilute and concentrated solutions,indicating that the proportion of the two excited states in the polymer chains had changed.For dilute MEH-PPV solutions,the blue-shifted absorption（at about 500 nm）and PL spectra show that ultrasonication also led to polymer chain degradation and thus shortened the effective conjugation length.For concentrated solutions,however,the peak positions of the absorption spectra remained unchanged.In addition,the effects of the solution temperatures on the optical spectra for the MEH-PPV solutions were also discussed.

Electronic states and molecular orientation of ITIC film

ITIC is the milestone of non-fullerene small molecule acceptors used in organic solar cells. We study the electronic states and molecular orientation of ITIC film using photoelectron spectroscopy and x-ray absorption spectroscopy. The negative integer charge transfer energy level is determined to be 4.00 ± 0.05 eV below the vacuum level, and the ionization potential is 5,75 ±0.10 eV. The molecules predominantly have the face-on orientation on inert substrates as long as the surfaces of the substrates are not too rough. These results provide the physical understanding of the high performance of ITIC-based solar ceils, which also afford implications to design more advanced photovoltaic small molecules.

AB INITIO STUDY OF LOW-LYING ELECTRONIC STATES OF THE AsH_2 RADICAL

The equilibrium geometries,excitation energies,force constants and vibrational frequencies for the low-ly- ing electronic states X ~2B_1,~2A_1,~2B_2 and ~2A_2 of the AsH_2 radical have been calculated at the MRSDCI level with a 3-21G~* basis set.Our calculated geometries,excitation enegies and vibional frequencies for the X ~2B_1 and ~2A_1 states are in good agreement with available experimental data.The electronic transition dipole mo- ments,oscillator strengths for the ~2A_1→X ~2B_1 and ~2A_2→X ~2B_1 transitions,radiative lifetimes for the ~2A_1 and ~2A_2 states are calculated based on the MRSDC^1 wavefunctions,predicting results in reasonable agreement with available experiment.

Effects of initial electronic state on vortex patterns in counter-rotating circularly polarized attosecond pulses

We theoretically investigate the effects of different electronic states as the initial state on the vortex patterns in photoelectron momentum distributions(PMDs)from numerical solutions of the two-dimensional(2D)time-dependent Schrodinger equation(TDSE)of He^(+)with a pair of counter-rotating circularly polarized attosecond pulses.It is found that the number of spiral arms in vortex patterns is equal to the number of the absorbed photons when the initial state is the ground state.However,the number of spiral arms in vortex patterns is always two more than the number of the absorbed photons when the initial state is the excited state.This sensitivity is attributed to the initial electron density distribution.In addition,we have demonstrated the PMDs for different initial electronic states with the same wavelengths and analyzed their corresponding physical mechanisms.It is illustrated that the method presented can be employed to effectively control the distribution of the electron vortices.

Low-energy electronic states of carbon nanocones in an electric field

The low-energy electronic states and energy gaps of carbon nanocones in an electric field are studied using a single-?-band tight-binding model. The analysis considers five perfect carbon nanocones with disclination angles of 60°, 120°, 180°, 240° and 300°, respectively. The numerical results reveal that the low-energy electronic states and energy gaps of a carbon nanocones are highly sensitive to its geometric shape(i.e. the disclination angle and height), and to the direction and magnitude of an electric field. The electric field causes a strong modulation of the state energies and energy gaps of the nanocones, changes their Fermi levels, and induces zero-gap transitions. The energy-gap modulation effect becomes particularly pronounced at higher strength of the applied electric field, and is strongly related to the geometric structure of the nanocone.

MRSDCI STUDIES OF LOW-LYING ELECTRONIC STATES OF THE N_2F^+ MOLECULE

Ab initio electronic structure calculations are reported for low-lying electronic states,X ~1Σ^+and A ~1Π of the N_2F^+ molecule.Geometric parameters for the ground state X ~1Σ^+ are predicted by means of mul- tireference single and double excitation configuration interaction(MRSDCI)calculations with a double zeta plus polarization(DZ+P)basis set.Vertical excitation energy for these two electronic states is determined using MRSDCI/DZ+P calculations at the ground state equilibrium geometry.The oscillator strength for the X^1Σ+→ A ~1Π transition and the radiative lifetime for the A^1Π state are calculated based on the MRSDCI wavefunc- tions.

Low-lying electronic states of CuN calculated by MRCI method

The high accuracy ab initio calculation method of multi-reference configuration interaction（MRCI） is used to compute the low-lying eight electronic states of CuN.The potential energy curves（PECs） of the X;∑;,1;Π,2;∑;,1;△,1;△,1;∑;,1;Π,and;∑;in a range of R=0.1 nm-0.5 nm are obtained and they are goodly asymptotes to the Cu（;S;） + N（;S;） and Cu（;S;）+N（;D;） dissociation limits.All the possible vibrational levels,rotational constants,and spectral constants for the six bound states of X;∑;,1;Π,2;∑;,1;△,1;∑;,and 1;Π are obtained by solving the radial Schrdinger equation of nuclear motion with the Le Roy provided Level 8.0 program.Also the transition dipole moments from the ground state X;∑;to the excited states 1;Π and 2;∑;are calculated and the result indicates that the 2;∑-X;∑ transition has a much higher transition dipole moment than the 1;Π-X;∑;transition even though the l;Π state is much lower in energy than the 2;∑;state.

Ab Initio Studies on Eight Electronic States of the BH_2 Radical

The present paper covers ab initio UHF calculations with a d, p-polarized basis set performed for eight electronic states of BH2 and the equilibrium geometries, electronic term values Tc and vibrational frequencies of the five stable states X2A1, 2B1, 2B2, 22A1 and 2A2. On the basis of the UHF results, the states 22B2. 2B1 and 32A1 are predicted to be unstable. The MP2/6-31G * * calculations were performed for the X2A1 and 2B1, states, and the calculated equilibrium geometries, Tc value and vibrational frequencies are similar to the UHF results. The MP2/6-31G * * studies on the reaction BH2→BH + H for the X2A1 and 2B1 states were carried out and the HB-H bond energies of these two states were calculated.

Modulation of Electronic States in Bimetallic-doped Nitrogen-Carbon Based Nanoparticles for Enhanced Oxygen Reduction Kinetics

Controlling the local electronic structure of active ingredients to improve the adsorption desorption characteristics of oxygen-containing intermediates over the electrochemical liquid-solid interfaces is a critical challenge in the field of oxygen reduction reaction(ORR)catalysis.Here,we offer a simple approach for modulating the electronic states of metal nanocrystals by bimetal co-doping into carbon-nitrogen substrate,allowing us to modulate the electronic structure of catalytic active centers.To test our strategy,we designed a typical bimetallic nanoparticle catalyst(Fe-Co NP/NC)to flexibly alter the reaction kinetics of ORR.Our results from synchrotron Xray absorption spectroscopy and X-ray photoelectron spectroscopy showed that the co-doping of iron and cobalt could optimize the intrinsic charge distribution of Fe-Co NP/NC catalyst,promoting the oxygen reduction kinetics and ultimately achieving remarkable ORR activity.Consequently,the carefully designed Fe-Co NP/NC exhibits an ultra-high kinetic current density at the operating voltage(71.94 mA/cm^(2)at 0.80 V),and the half-wave potential achieves 0.915 V,which is obviously better than that of the corresponding controls including Fe NP/NC,Co NP/NC.Our findings provide a unique perspective for optimizing the electronic structure of active centers to achieve higher ORR catalytic activity and faster kinetics.

Optimizing the electronic spin state and delocalized electron of NiCo_(2)(OH)_(x)/MXene composite by interface engineering and plasma boosting oxygen evolution reaction

The electrocatalytic activity of transition-metal-based compounds is closely related to the electronic configuration.However,optimizing the surface electron spin state of catalysts remains a challenge.Here,we developed a spin-state and delocalized electron regulation method to optimize oxygen evolution reaction(OER)performance by in-situ growth of NiCo_(2)(OH)_(x) using Oswald ripening and coordinating etching process on MXene and plasma treatment.X-ray absorption spectroscopy,magnetic tests and electron paramagnetic resonance reveal that the coupling of NiCo_(2)(OH)_(x) and MXene can induce remarkable spin-state transition of Co^(3+)and transition metal ions electron delocalization,plasma treatment further optimizes the 3 d orbital structure and delocalized electron density.The unique Jahn-Teller phenomenon can be brought by the intermediate spin state(t2 _(g)^(5) e_(g)^(1))of Co^(3+),which benefits from the partial electron occupied egorbitals.This distinct electron configuration(t2_(g)^(5) e_(g)^(1))with unpaired electrons leads to orbital degeneracy,that the adsorption free energy of intermediate species and conductivity were further optimized.The optimized electrocatalyst exhibits excellent OER activity with an overpotential of 268 m V at 10 m A cm^(-2).DFT calculations show that plasma treatment can effectively regulate the d-band center of TMs to optimize the adsorption and improve the OER activity.This approach could guide the rational design and discovery of electrocatalysts with ideal electron configurations in the future.

Theoretical study on stability and nonlinear optical properties of tetrahydropyrrole diradical and its isoelectronic systems in different electronic states

The polarizabilities and hyperpolarizabilities of the tetrahydropyrrole diradical in different electronic states have been investigated using ab initio and density functional theory （DFT） methods combined with the finite field （FF） approach. The polarizability average value as is a maximum for the singlet state, while that for the closed-shell is a minimum. The trend in second hyperpolarizability average value yis in good agreement with that for as The yvalues of the singlet and triplet states are, respectively, about 3 and 2 times larger than that of the closed-shell. The order of the first hyperpolarizability total effective value βtot is βot （closed shell） βtot （singlet） 〉 βtot （triplet）. The as, βtot, and 7 values of different electronic states obtained using the B3LYP and MP4SDQ methods are close to those obtained using the reliable CCSD method. The nonlinear optical （NLO） properties of two systems isoelectronic with the tetrahydropyrrole diradical-cyclopentane and tetrahydrofuran diradicalsshow that the polarizabilities and hyperpolarizabilities of these systems are all smaller than those of the tetrahydropyrrole diradical in the three electronic states.

Electronic States of Some Semiconductor Clusters

Potential surfaces and equilibrium geometries of InAs 2, In 2As, InAs 2 + and In 2As + were studied using the complete active space multi configuration self consistent field (CASMCSCF) technique. Two electronic states, namely 2B 2 and 2B 1, were found to prevail as the ground states for the InAs 2 and In 2As trimers, respectively. The corresponding adiabatic ionization energies were computed and the leading configurations of the ground states were analyzed according to the wavefunctions.

An Accurate Calculation of Potential Energy Curves and Transition Dipole Moment for Low-Lying Electronic States of CO

In this paper, potential energy curves for the X1∑＋, a3П, a＇∑＋, da△, A1П and I∑- states of CO have been calculated using complete active space se1f-consistent field and multi-reference configuration interaction methods. The calculations have been performed at 108 nuclear separations from 0.7 to 4.0 A by the aug-cc-PVSZ basis set. Spectroscopic constants for the six low-lying electronic states are found in good agreement with experimental data. The vibrational states of the X1∑＋ and A1П states are also calculated, which are reliable and accurate by comparison with the experimental data and the other theoretical values. The transition dipole moment （TDM） shows that the TDM of the two states （X1∑＋→A1П）are reduced strongly with increase of bond length.

Analysis and Efficient Solution of Stationary Schrodinger Equation Governing Electronic States of Quantum Dots and Rings in Magnetic Field

In this work the one-band effective Hamiltonian governing the electronic states of a quantum dot/ring in a homogenous magnetic field is used to derive a pair/quadruple of nonlinear eigenvalue problems corresponding to different spin orientations and in case of rotational symmetry additionally to quantum number±ℓ.We show,that each of those pair/quadruple of nonlinear problems allows for the minmax characterization of its eigenvalues under certain conditions,which are satisfied for our examples and the common InAs/GaAs heterojunction.Exploiting the minmax property we devise efficient iterative projection methods simultaneously handling the pair/quadruple of nonlinear problems and thereby saving up to 40%of the computational time as compared to the nonlinear Arnoldi method applied to each of the problems separately.

GGA+U study of the electronic energy bands and state density of the wurtzite In_(1-x)Ga_xN

The electronic band structures, densities of states （DOSs）, and projected densities of states （PDOSs） of the wurtzite In1-xGaxN with x=0, 0.0625, 0.125 are studied using the generalized-gradient approximation （GGA） and GGA＋U in density functional theory. Our calculations suggest that in the case of wurtzite InN it is important to apply an on-site Hubbard correction to both the d states of indium and the p states of nitrogen in order to recover the correct energy level symmetry and obtain a reliable description of the InN band structure. The method is used to study the electronic properties of the wurtzite In1-xGaxN. The conduction band minimum （CBM） energy increases, while the valence band maximum （VBM） energy decreases with the increase of the gallium concentration. The effect leads to broadening the band gap （BG） and the valence band width （VBW）. Furthermore, the compressive strain in the crystal can cause the BG and the VBW to increase with the increase of gallium concentrations.