Potential Energy Research Articles

Rural transformation and the future of China's "granary": A perspective on livelihood trajectories

Recent research demonstrates that the core features of agricultural and rural transformation in grain-dependent areas of the newly industrializing countries in East and Southeast Asia do not fully align with classical theories and paradigms. However, there is a lack of a theoretical model that illustrates the general patterns of rural evolution and transformation in these areas during structural transformation and outlines their future trajectories. Through case studies of a well-known grain base in China, this paper explores this issue using an analytical framework consisting of the trajectory of agricultural transformation associated with rural residents' livelihood changes and the trajectory of rural community restructuring induced by these livelihood changes. The results show that, since structural transformation, the grain-dependent countryside of China has roughly undergone an evolution from a stage of relative isolation and self-sufficiency, marked by agricultural involution, to a stage of accelerating factor flows between cities and the countryside, marked by part-time livelihoods, and finally to the current stage of accumulating "potential energies" for rural restructuring, marked by population aging. Meanwhile, challenges to the further transformation of the countryside are rooted in the socioeconomic characteristics of the middle-income period, which underscores the significance of overcoming the middle-income trap. Finally, we propose theoretical patterns for the future trajectories of China's grain-dependent countryside through the scenario analysis based on overcoming the middle-income trap and discuss the implications for rural revitalization in these areas.

Boron oxide B5O6 and B5O6− clusters with a hexagonal B3O3 ring: Overturn of potential energy landscapes by one electron

Boron oxide clusters feature novel structures and nonclassical chemical bonding, owing to the electron deficiency of boron. We report on a quantum chemical study on structural, electronic, and bonding properties of B5O6 and B5O6− clusters through global-minimum (GM) searches and electronic structure calculations. The neutral B5O6 cluster is shown to assume a GM structure composed of a boroxol core, a terminal boronyl, and a terminal BO2 group, which differs distinctly from anion GM B5O6− cluster. The latter has a boroxol core and three terminal ligands: two boronyls and one O− unit. One electron completely overturns the potential energy surfaces of the present system, which is governed by the nature of frontier molecular orbitals in two types of structures. As a consequence, one electron can make a difference by as much as 2 − 3 eV. The structural transformation is also elucidated using a proposed possible mechanism of boronyl ligand migration.

Determination of biomass energy potential based on regional characteristics using adaptive clustering method

Determining the energy potential of biomass is the first step in selecting the most suitable and efficient energy conversion technology based on regional characteristics. The approach to estimating and determining biomass potential generally uses geospatial technology related to collecting and processing data about mapping an area. Unfortunately, this method is inadequate for simulating the interaction between variables, nor can it provide accurate predictions for the biomass supply chain. As a result, the results obtained from this method tend to be biased and macro, particularly in regions experiencing rapid land-use development. In this paper, the author has developed a clustering methodology with a fuzzy c-means (FCM) algorithm to determine biomass energy potential based on regional characteristics to produce data clusters with high accuracy. Grouping the characteristics of clustering-based areas involves grouping physical or abstract objects into classes or similar objects.

Optimal cleaning robot on solar panels with time-sequence input based on internet of things

Solar panels are the main component of solar power generation systems, and they function by converting solar energy into electrical energy. Indonesia has great potential for solar energy. Solar panels will work optimally at temperatures of 25 °C to 28 °C. The greater the temperature of the solar panel, the more power generated by the panel. The influence of solar radiation intensity can be caused by dust and animal droppings attached to the surface of the solar panel module. If the surface of a solar panel is covered with dust or dirt, which can block the entry of solar radiation, the resulting power output is not optimal. The aim of this research is to design and implement an automatic cleaning system for solar power plants. The system used is using ESP32 based on the Blynk application and adding internet of things (IoT) devices with a cleaning method using pumped water spraying, then assisted with wipers which have silicon rubber material to clean dust and dirt. Based on the cleaning optimization simulation calculations, we found that the optimal or efficient cleaning condition was once a month, with an efficiency of 75.17%.

Architectural coatings and temperature Adaptive radiative cooling strategies applied in ten climate zones in China: Annual energy consumption Reductions and potentials

This research evaluates the energy-saving potential of high-reflectivity building materials, including three common coating types—normal (absorptivity 0.8, emissivity 0.8), cooling (absorptivity 0.2, emissivity 0.9), supercooling (absorptivity 0.05, emissivity 0.95), and Temperature-Adaptive Radiative Cooling (TARC) materials across 49 representative cities within ten climate zones in China using computational fluid dynamics simulations combined with the Demand.ninja energy consumption model. The results reveal that optimal solar absorptivity varies significantly between different climate zones, with higher absorptivity benefiting colder regions and lower absorptivity benefiting hotter regions. Urban microclimate simulations confirm that low solar absorption materials effectively reduce wall temperatures during the daytime and boost overall cooling energy savings, despite a slight increase in ambient air temperature. Building height-to-width ratios also influenced energy efficiency, with the best performance observed at a ratio of unity for both cooling and supercooling materials. Additionally, tests on the Temperature-Adaptive Radiative Cooling (TARC) materials demonstrate that TARCs offer significant energy-saving advantages, achieving an annual saving of 23.1 billion kWh across China by effectively balancing heating and cooling demands across different seasons. This superior performance is primarily attributed to TARCs’ ability to mitigate increased heating energy demands often associated with conventional cooling materials, especially in regions with substantial winter heating needs. Present research has highlighted the importance of climate-specific building material strategies and the potential of innovative materials like TARC for reducing energy consumptions, and this could favour the low carbon urban development.

Analytical and Experimental Study on a Versatile Landing System with Shock Response Mechanism

This paper introduces a versatile, passive-landing system designed for various landing operations such as planetary exploration missions, emergency landings of unmanned aerial vehicles (UAVs), and so on. The system leverages energy and momentum exchange mechanisms, incorporating two spring units and a detachable flyaway component to ensure smooth and safe landings. Initially, the kinetic energy of the lander is converted into potential energy stored in the spring units. A switch mechanism then releases this stored energy, converting it back into kinetic energy and transferring momentum to the flyaway part. This process effectively suppresses rebound and reduces acceleration, ensuring a soft landing. A key advantage of this mechanism is its high robustness against variations in initial-fall height. The energy stored in the spring units adjusts according to the falling height, enhancing the system adaptability. The system performance is evaluated through one-dimensional simulations to assess rebound height and acceleration, and two-dimensional simulations to evaluate its ability to prevent tip-over. An experimental setup further validates the system-rebound suppression capability. Results from both simulations and experiments confirm the superior system performance in minimizing rebound, reducing acceleration, and preventing rotational motion during landing.

Hydrothermal co-carbonization of hazelnut and pistachio shells to hydrochar as potential energy source: Synergistic effects of process parameters on hydrochar characteristics

Hydrothermal co-carbonization of hazelnut and pistachio shells to hydrochar as potential energy source: Synergistic effects of process parameters on hydrochar characteristics

Using mode shape residuals for model updating of a nonlinear structure featuring 1:1 internal resonance

Internal resonance isa unique phenomenon in nonlinear structures. It can lead to pronounced energy transfer between vibrating modes, causing unexpected stress concentrations in local areas and posing a risk to structural integrity. This paper presents a general model updating procedure for nonlinear structures with such internal resonances using experimentally measured data. The test involves using multiple amplitudes of sinusoidal excitations to drive the structure to several required vibration amplitudes, enabling the underlying linear dynamics, uncoupled nonlinear dynamics, and internal resonances to be activated individually. The underlying linear system, uncoupled nonlinear terms, and cross-coupling terms in the dynamic equation are updated sequentially, with updating the cross-coupling terms being the most challenging task. Unlike conventional practices that heuristically pre-assume a model for the cross-coupling force terms, this paper minimises their number by using the coupling potential energies and identifies their type via an interaction map. A novel mode shape residual is then proposed to tune the coefficients of the cross-coupling terms, which allows energy transfer between coupled modes to be captured quantitatively. A diesis-like structure featuring 1:1 bending-torsion coupling was experimentally investigated using multi-level stepped-sine excitations to demonstrate the proposed model updating procedure. The vibrations of its first resonance veered from a bending-dominant motion to a bending-torsion coexisting motion as the driving forces increased, indicating strong amplitude-dependent mode shapes on the occurrence of internal resonance. The experimental data also showed that the softening and hardening trend of the torsional mode was dependent on the vibration amplitude of the bending mode, a peculiar vibration phenomenon seldom reported for realistic structures in the literature. Using the proposed model updating procedure, a two-mode coupled nonlinear model was identified from the frequency response functions and validated by comparing the backbone curves and amplitude-dependent mode shapes. Results showed that the updated model could predict the resonant vibration patterns of the structure away from and around its internal resonance with sufficient accuracy. It was also revealed that the softening and hardening behaviours of the torsional mode were attributed to different branches of Nonlinear Normal Modes (NNMs).

Prediction of building-scale solar energy potential in urban environment based on parametric modelling and machine learning algorithms

Prediction of building-scale solar energy potential in urban environment based on parametric modelling and machine learning algorithms

Unlocking the energy potential of rechargeable zinc batteries: Comprehensive insights into aqueous electrolyte design

Unlocking the energy potential of rechargeable zinc batteries: Comprehensive insights into aqueous electrolyte design

Simplified Multireference Coupled-Cluster Methods: Hybrid Approaches With Averaged Coupled Pair Theories.

We define an approximation to the internally contracted multireference coupled-cluster method with single and double excitations by a hybrid approach. The rationale is to treat the external pair energy contributions by the coupled-cluster method, which provides accurate results for a large part of the correlation energy while being tractable as the involved pair cluster operators commute. For the internal and semi-internal contributions, for which the coupled-cluster part becomes involved due to non-commuting operators, a linearized approach based on the coupled-electron pair approximation (CEPA) is used. For the latter, the CEPA(0) method, the averaged coupled pair functional (ACPF), the averaged quadratic coupled-cluster (AQCC) method, and the averaged CEPA method are tested. We test the methods concerning size consistency, potential energy curves for C2, N2, CN, and O3 and for the singlet-triplet splitting of ortho-, meta-, and para-benzynes. Our results show that AQCC provides the most accurate results and stable performance. The main drawback of the method is that it shows small violations of size consistency.

Minimum Energy Conical Intersection Optimization Using DFT/MRCI(2).

The combined density functional theory and multireference configuration interaction (DFT/MRCI) method is a semiempirical electronic structure approach that is both computationally efficient and has predictive accuracy for the calculation of electronic excited states and for the simulation of electronic spectroscopies. However, given that the reference space is generated via a selected-CI procedure, a challenge arises in the construction of smooth potential energy surfaces. To address this issue, we treat the local discontinuities that arise as noise within the Gaussian progress regression framework and learn the surfaces by explicitly incorporating and optimizing a white-noise kernel. The characteristic polynomial coefficient surfaces of the potential matrix, which are smooth functions of nuclear coordinates even at conical intersections, are learned in place of the adiabatic energies and are used to optimize the DFT/MRCI(2) minimum energy conical intersection geometries for representative intersection motifs in the molecules ethylene, butadiene, and fulvene. One consequence of explicitly treating the noise in the surfaces is that the energy difference cannot be made arbitrarily small at points of nominal intersection. Despite the limitations, however, we find the structures as well as the branching spaces to compare well with ab initio MRCI and conclude that this approach is a viable method to learn a smooth representation of DFT/MRCI(2) surfaces.

Decoherence and vibrational energy relaxation of the electronically excited PtPOP complex in solution.

Understanding the ultrafast vibrational relaxation following photoexcitation of molecules in a condensed phase is essential to predict the outcome and improve the efficiency of photoinduced molecular processes. Here, the vibrational decoherence and energy relaxation of a binuclear complex, [Pt2(P2O5H2)4]4- (PtPOP), upon electronic excitation in liquid water and acetonitrile are investigated through direct adiabatic dynamics simulations. A quantum mechanics/molecular mechanics (QM/MM) scheme is used where the excited state of the complex is modeled with orbital-optimized density functional calculations while solvent molecules are described using potential energy functions. The decoherence time of the Pt-Pt vibration dominating the photoinduced dynamics is found to be ∼1.6ps in both solvents. This is in excellent agreement with experimental measurements in water, where intersystem crossing is slow (>10 ps). Pathways for the flow of excess energy are identified by monitoring the power of the solvent on vibrational modes. The latter are obtained as generalized normal modes from the velocity covariances, and the power is computed using QM/MM embedding forces. Excess vibrational energy is found to be predominantly released through short-range repulsive and attractive interactions between the ligand atoms and surrounding solvent molecules, whereas solute-solvent interactions involving the Pt atoms are less important. Since photoexcitation deposits most of the excess energy into Pt-Pt vibrations, energy dissipation to the solvent is inefficient. This study reveals the mechanism behind the exceptionally long vibrational coherence of the photoexcited PtPOP complex in solution and underscores the importance of short-range interactions for accurate simulations of vibrational energy relaxation of solvated molecules.

The impact of antimony on all-inorganic lead-free perovskites: progress in optical advancement and applications.

The incorporation of Sb3+ ions into all-inorganic halide lead-free perovskites bestows them with remarkable photoluminescence characteristics, including an extensive color tuning range, elevated photoluminescence quantum yield (PLQY), and reversible color transitions, which hold significant promise for applications in light-emitting diodes, anti-counterfeiting encryption technologies, and photodetectors. Sb3+ ions not only create new optical absorption channels but also can be integrated into these materials as activators or sensitizers to modulate the bandgap and band structure. This review focuses on the optical properties of Sb3+ ion-doped lead-free halide perovskites while examining potential energy transfer pathways across various doping systems. It reviews the recent research progress of Sb3+ ion-doped lead-free perovskites within different frameworks, addressing influencing factors, strategies for enhancing PL intensity, and prospective applications. Ultimately, it outlines the challenges that lie ahead and proposes viable solutions for further exploration of Sb-doped lead-free perovskites.

Energetic and Electronic Properties of AcX and LaX (X = O and F).

The bonding and spectroscopic properties of LaX and AcX (X = O and F) diatomic molecules were studied by high-level ab initio CCSD(T) and SO-CASPT2 electronic structure calculations. Bond dissociation energies (BDEs) were calculated at the Feller-Peterson-Dixon (FPD) level. Potential energy curves and spectroscopic constants for the lowest-lying spin-orbit Ω states were obtained at the SO-CASPT2/aQ-DK level. A dense manifold of excited states was described for the monofluorides with the ground states well separated from the excited states. The spectroscopic parameters were in good agreement with those reported experimentally for LaO and LaF. For the diatomic molecules containing actinides, no experimental data of these parameters was found, but the results were consistent with other high-level calculations. The BDEs calculated at the FPD level were 791.3 (LaO), 705.2 (AcO), 650.0 (LaF), and 678.6 (AcF) kJ/mol. The NBO analysis showed that the monofluorides are essentially ionic, which explains why the BDE(AcF) is higher than BDE(LaF); for the monoxides, covalent contributions involving the d orbitals of the metal and the p orbitals of the oxygen are stronger for LaO than AcO, which explains the higher BDE for LaO. The bond orders are predicted to be 2 for LaF and AcF, 3 for AcO, and higher than 3 for LaO.

Molecular dynamics simulations of functionalized hBN nanopores in water: Ab initio force field and implications for water desalination.

Heteropolar two-dimensional materials, including hexagonal boron nitride (hBN), are promising candidates for seawater desalination and osmotic power harvesting, but previous simulation studies have considered bare, unterminated nanopores in molecular dynamics (MD) simulations. There is presently a lack of force fields to describe functionalized nanoporous hBN in aqueous media. To address this gap, we conduct density functional theory (DFT)-based abinitio MD simulations of hBN nanopores surrounded by water molecules. The results reveal a high propensity for hydrogen (H) and hydroxyl (OH) functionalization at boron edges, while nitrogen edges are functionalized with H and occasionally with oxygen (O), highlighting a route to tune membranes. We demonstrate the role of the Grotthuss mechanism during the functionalization of hBN edges in water. We develop high-fidelity force fields for H- and OH-functionalized hBN nanopores using potential energy surface fitting based on DFT calculations. The nonbonded parameters for H functionalization are obtained by training a force field for borazine (B3N3H6). We find that the proposed force field enables stable MD simulations of water/ion transport through B- and N-terminated hBN nanopores. Our results also indicate that previous studies that considered bare nanopores without functional groups overestimated the water flux and underestimated the ionic rejection of nanoporous hBN. Overall, our work is expected to enable the realistic modeling of edge-functionalized hBN in aqueous media for various application areas.

Interstellar spectroscopic detection of HC(S)NC and DC(S)NC.

The detection of HC(S)CN in TMC-1 suggests that HC(S)NC may also exist. To aid in its possible detection, HC(S)NC and its deuterated isotopologue DC(S)NC were investigated via high-level abinitio methods, specifically CCSD(T) and CCSD(T)-F12. By utilizing multidimensional potential energy surfaces derived from explicitly correlated coupled-cluster calculations, we analyzed their geometrical parameters, vibrational frequencies, rotational constants, and a comprehensive set of spectroscopic constants generated via the vibrational second-order perturbation theory, vibrational self-consistent field, and vibrational configuration interaction theory(VCI) approaches. HC(S)NC is thermodynamically stable relative to the HCS + NC dissociation limit, with a predicted bond dissociation energy of 4.1eV. The calculated vibrational frequencies are characterized by two bright modes that correspond to CN stretching. Finally, HC(S)NC shows a significant dipole moment, predicted to be 1.9D, making its detection via rotational spectroscopy plausible.

Excited electronic states of Na2 and K2: The potential for long-lived "reservoir" states leading to collision induced population inversions.

Potential energy curves (PECs) for the spin-free (ΛS) and spin-orbit (Ω) states associated with the four lowest-lying dissociation channels of Na2 and K2 were calculated at the SA-CASSCF/SO-CASPT2/aug-cc-pwCVQZ-DK level. The PECs of Na2 were consistent with the experimental data and with the FS-CCSD (2,0) calculations, reproducing the double-well and the "shelf" character for some of the potentials of the excited states. For K2, the PECs behaved in a similar way and the spectroscopic parameters for the ground and the excited states are in good agreement with the available experimental values. The dissociation energy of K2 was predicted to be De = 4454cm-1, within an agreement of 5cm-1 with the experiments. For Na2, De = 5789cm-1 compared to the experimental value of 6022cm-1. The inclusion of spin-orbit coupling effects resulted in avoided crossings, which affect the PECs. Spin-orbit changes the predicted curves for some excited Ω states arising from ΛS states that overlap each other, affecting their associated vibrational frequencies and bond distances. The current studies of the low-lying states in K2 reveal a similar structure to those of Na2, which suggests the accessibility of long-lived energy storing reservoir states and possible population inversions in K2 following prior experimental work on the reaction of halogen atoms with Na3 to produce excited states of Na2.

Gas-phase Conformational Landscape and Ring-puckered Structure of 1-aminoindane.

Indane-based molecules are effective scaffolds for different pharmaceutical products, so it is relevant to analyze the relation between structure and functionality in indane derivatives. Here, we have characterized the conformational landscape and molecular structure of 1-aminoindane in the gas phase using chirped-excitation Fourier-transform microwave spectroscopy and computational methods. The rotational spectrum confirmed the presence of two conformers, which were identified based on their rotational constants and 14N nuclear quadrupole coupling tensor elements. The observed conformers share the cyclopentane puckering and amino equatorial configuration but differ in the orientation of the amino group hydrogens. The spectral analysis further allowed the observation of all monosubstituted 13C and 15 N isotopologues in natural abundance for the most stable isomer, allowing a precise structural determination for this species. Structural information was derived using the substitution ( ) and effective vibrational ground state ( ) methods, revealing that the structure of 1-aminoindane is very similar to that of indane. A calculation of the potential energy surface along the pathway for the conversion between the most stable equatorial species permitted to rationalize the non-observation of additional conformers via molecular relaxation during the adiabatic expansion. The computational results include ab initio (MP2) and DFT methods (B3LYP, ωB97X-D and M06-2X).

Alchemical harmonic approximation based potential for iso-electronic diatomics: Foundational baseline for Δ-machine learning.

We introduce the alchemical harmonic approximation (AHA) of the absolute electronic energy for charge-neutral iso-electronic diatomics at fixed interatomic distance d0. To account for variations in distance, we combine AHA with this ansatz for the electronic binding potential, E(d)=(Eu-Es)Ec-EsEu-Esd/d0+Es, where Eu, Ec, Es correspond to the energies of the united atom, calibration at d0, and the sum of infinitely separated atoms, respectively. Our model covers the two-dimensional electronic potential energy surface spanned by distances of 0.7-2.5Å and differences in nuclear charge from which only one single point (with elements of nuclear charge Z1, Z2, and distance d0) is drawn to calibrate Ec. Using reference data from pbe0/cc-pVDZ, we present numerical evidence for the electronic ground-state of all neutral diatomics with 8, 10, 12, and 14 electrons. We assess the validity of our model by comparison to legacy interatomic potentials (harmonic oscillator, Lennard-Jones, and Morse) within the most relevant range of binding (0.7-2.5Å) and find comparable accuracy if restricted to single diatomics and significantly better predictive power when extrapolating to the entire iso-electronic series. We also investigated Δ-learning of the electronic absolute energy using our model as a baseline. This baseline model results in a systematic improvement, effectively reducing training data needed for reaching chemical accuracy by up to an order of magnitude from ∼1000 to ∼100. By contrast, using AHA+Morse as a baseline hardly leads to any improvement and sometimes even deteriorates the predictive power. Inferring the energy of unseen CO converges to a prediction error of ∼0.1 Ha in direct learning and ∼0.04 Ha with our baseline.