Intermolecular Distance Research Articles

Spatial Decay and Limits of Quantum Solute-Solvent Interactions.

Molecular excitations in the liquid-phase environment are renormalized by the surrounding solvent molecules. Herein, we employ the GW approximation to investigate the solvation effects on the ionization energy of phenol in various solvent environments. The electronic effects differ by up to 0.4 eV among the five investigated solvents. This difference depends on both the macroscopic solvent polarizability and the spatial decay of the solvation effects. The latter is probed by separating the electronic subspace and the GW correlation self-energy into fragments. The fragment correlation energy decays with increasing intermolecular distance and vanishes at ∼9 Å, and this pattern is independent of the type of solvent environment. The 9 Å cutoff defines an effective interacting volume within which the ionization energy shift per solvent molecule is proportional to the macroscopic solvent polarizability. Finally, we propose a simple model for computing the ionization energies of molecules in an arbitrary solvent environment.

Asymmetric rotations and dimerization driven by normal to modulated phase transition in 4-biphenylcarboxy coupled L-phenylalaninate.

Amongst the derivatives of 4-biphenylcarboxylic acid and amino acid esters, the crystal structure of 4-biphenylcarboxy-(L)-phenylalaninate is unusual owing to its monoclinic symmetry within a pseudo-orthorhombic crystal system. The distortion is described by a disparate rotational property around the chiral centers (ϕchiral ≃ -129° and 58°) of the two molecules in the asymmetric unit. Each of these molecules comprises planar biphenyl moieties (ϕbiphenyl = 0°). Using temperature-dependent single-crystal X-ray diffraction experiments we show that the compound undergoes a phase transition below T ∼ 124 K that is characterized by a commensurate modulation wavevector, q = δ(101), δ = ½. The (3+1)-dimensional modulated structure at T = 100 K suggests that the phase transition drives the biphenyl moieties towards noncoplanar conformations with significant variation of internal torsion angle (ϕmaxbiphenyl ≤ 20°). These intramolecular rotations lead to dimerization of the molecular stacks that are described predominantly by distortions in intermolecular tilts (θmax ≤ 20°) and small variations in intermolecular distances (Δdmax ≃ 0.05 Å) between biphenyl molecules. Atypical of modulated structures and superstructures of biphenyl and other polyphenyls, the rotations of individual molecules are asymmetric (Δϕbiphenyl ≈ 5°) while ϕbiphenyl of one independent molecule is two to four times larger than the other. Crystal-chemical analysis and phase relations in superspace suggest multiple competing factors involving intramolecular steric factors, intermolecular H-C...C-H contacts and weak C-H...O hydrogen bonds that govern the distinctively unequal torsional properties of the molecules.

Experimental and mechanism investigation on flowability and wax deposition of waxy crude oil with dissolved CH4 by pressurized laboratory apparatus

In offshore oilfields, crude oils often contain dissolved gas, and are unavoidably transported under pressure. However, the flowability and wax deposition of crude oils with dissolved gas are rarely investigated. In this paper, Methane (CH4) was used as a similar substitute for the dissolved gas in crude oils, and a series of pressurized laboratory apparatuses were developed to study the influencing mechanism of dissolved CH4 on the flowability and wax deposition of Changqing waxy crude oil. It was found that with the increase of the dissolved CH4 pressure, the crude oil flowability was improved, and the wax deposition rate was inhibited. However, the wax appearance temperature (WAT), the average wax content of wax deposits, and the mass of wax diffused into wax deposits all increased accordingly. This was mainly attributed to the influence of dissolved CH4, which can effectively increase the intermolecular distance between wax molecules, decrease the intermolecular forces, and weaken the strength of wax crystals to overlap each other. The improvement of rheological properties, on the one hand, promotes the diffusion of wax molecules, which leads to the increase in the mass of wax diffused into wax deposits; on the other hand, it increases the wax content required for the formation of wax deposits according to the dynamic gelation mechanism, thus resulting in the decrease of wax deposition rate. Also, the wax stripping effect during the deposition and depressurization processes cannot be ignored. The research results have guiding significance for the optimal design of the gathering and transportation pipeline network and the calculation of wax deposition.

Molecular dynamics simulation studies of 1,3-dimethyl imidazolium nitrate ionic liquid with water.

The fundamental understanding of intermolecular interactions of ionic liquids (ILs) with water is essential in predicting IL-water thermodynamic properties. In this study, intermolecular or noncovalent interactions were studied for 1,3-dimethyl imidazolium [DMIM]+ cation and nitrate [NO3]- anion with water, employing quantum mechanics and molecular dynamics simulations. Molecular dynamics simulations were performed using a revised multipolar polarizable force field. The effect of water on ionic liquids was evaluated in terms of thermodynamic and dynamic properties. Thermodynamic properties included liquid densities ρ, excess molar volumes ΔVE, and liquid structures gr. Dynamic properties included self-diffusion coefficients D of mixture constituents as a function of water concentration. The density of ionic liquid-water mixtures monotonically decrease with increasing concentration of water. A negative excess volume was obtained for low and high water concentrations, demonstrating strong intermolecular interactions of water with ionic liquid components. Liquid structures of ionic liquid-water mixtures revealed a tendency for anions to interact with cations at shorter intermolecular distances when the water concentration is increased. Diffusion rates were found to increase for all mixture components with increase in the fraction of water. A significant change in the diffusion rate was found at ∼0.3 weight fraction of water. However, the water self-diffusion coefficient was dominant at all concentrations. The ratio of water/anion and anion/cation self-diffusion coefficients was found to decrease linearly with increasing concentration of water molecules.

Medium-Ring Strategy Enables Multiple Resonance Emitters with Twisted Geometry and Fast Spin-Flip to Suppress Efficiency Roll-Off.

Suppressing aggregation-caused quenching (ACQ) effect and reducing device efficiency roll-off are both crucial yet challenging for multi-resonance (MR) emitters. Herein, we put forward a medium-ring strategy to design efficient MR emitters that feature heptagonal tribenzo[b,d,f]azepine (TBA) donors. The highly twisted conformation enlarges the intermolecular distances between the MR-emitting cores, and thus suppresses ACQ effect. Meanwhile, the introduction of heptagonal donors enhances spin-orbital coupling, so as to accelerate reverse intersystem crossing (RISC) process. This medium-ring strategy gives rise to the first example of blue MR emitter that simultaneously possesses radiative decay rate as fast as 108 s-1 and RISC rate as fast as 106 s-1 . Accordingly, DTBA-B2N3 enables to assemble high-performance blue organic light-emitting diodes (OLEDs) with maximum external quantum efficiency (EQEmax ) of 30.9 % and alleviated efficiency roll-off (EQE1000 : 20.5 %).

Medium‐Ring Strategy Enables Multiple Resonance Emitters with Twisted Geometry and Fast Spin‐Flip to Suppress Efficiency Roll‐Off

AbstractSuppressing aggregation‐caused quenching (ACQ) effect and reducing device efficiency roll‐off are both crucial yet challenging for multi‐resonance (MR) emitters. Herein, we put forward a medium‐ring strategy to design efficient MR emitters that feature heptagonal tribenzo[b,d,f]azepine (TBA) donors. The highly twisted conformation enlarges the intermolecular distances between the MR‐emitting cores, and thus suppresses ACQ effect. Meanwhile, the introduction of heptagonal donors enhances spin‐orbital coupling, so as to accelerate reverse intersystem crossing (RISC) process. This medium‐ring strategy gives rise to the first example of blue MR emitter that simultaneously possesses radiative decay rate as fast as 108 s−1 and RISC rate as fast as 106 s−1. Accordingly, DTBA‐B2N3 enables to assemble high‐performance blue organic light‐emitting diodes (OLEDs) with maximum external quantum efficiency (EQEmax) of 30.9 % and alleviated efficiency roll‐off (EQE1000: 20.5 %).

Accuracy of Measurements of Thermophysical Parameters by Dual-Beam Thermal-Lens Spectrometry.

Thermal-lens spectrometry is a sensitive technique for determination of physicochemical properties and thermophysical parameters of various materials including heterogeneous systems and nanoparticles. In this paper, we consider the issues of the correctness (trueness) of measurements of the characteristic time of the thermal-lens effect and, thus, of the thermal diffusivity determined by dual-beam mode-mismatching thermal lensing. As sources of systematic errors, major factors-radiation sources, sample-cell and detector parameters, and general measurement parameters-are considered using several configurations of the thermal-lens setups, and their contributions are quantified or estimated. Furthermore, with aqueous ferroin and Sudan I in ethanol as inert colorants, the effects of the intermolecular distance of the absorbing substance on the correctness of finding the thermophysical parameters are considered. The recommendations for checking the operation of the thermal-lens setup to ensure the maximum accuracy are given. The results obtained help reducing the impact of each investigated factor on the value of systematic error and correctly measure the thermophysical parameters using thermal-lens spectrometry.

Spiral donor-based host materials for highly efficient blue thermally activated delayed fluorescence OLEDs

Spiral donor units have attracted extensive research focuses in designing highly emissive thermally activated delayed fluorescence (TADF) emitters. Herein, to reveal the significance of spiral donor units for constructing highly efficient host materials, several spiral donor-based host materials are developed. With the incorporation of spiral donor, increased intermolecular distance is achieved to reduce the concentration quenching effect of dopant. Moreover, the high triplet energy level of spiral donor can provide an additional energy transfer channel to further improve the device performance. Noteworthy, by connecting spiral donors or conventional carbazole unit with different electron-withdrawing units phenoxathiine 10,10-dioxide (PX) or phenoxathiine (PA), these hosts are given different photophysical properties of TADF, room-temperature phosphorescence (RTP) and conventional fluorescence (CF). The strong electron-withdrawing ability of PX is beneficial to the TADF character of spiral donor-based molecules, while the weak electron-withdrawing ability of PA is beneficial to the RTP property. Consequently, the blue OLEDs with DspiroAc-TRZ as a dopant emitter based on the hosts with TADF characters exhibit higher performance than those with RTP and CF properties, and excellent external quantum efficiency (EQE) of 36.1 % and current efficiency of 84.6 cd/A are achieved in a simple device structure. Furthermore, peak EQEs of 34.0 % and 33.0 % are achieved, when DspiroS-PX and DspiroS-PA hosted DspiroAc-TRZ are used to sensitize blue multi-resonance TADF emitter v-DABNA. Our work may shed new light on designing highly efficient host materials for TADF emitters.

Leveraging scaffold information to predict protein-ligand binding affinity with an empirical graph neural network.

Protein-ligand binding affinity prediction is an important task in structural bioinformatics for drug discovery and design. Although various scoring functions (SFs) have been proposed, it remains challenging to accurately evaluate the binding affinity of a protein-ligand complex with the known bound structure because of the potential preference of scoring system. In recent years, deep learning (DL) techniques have been applied to SFs without sophisticated feature engineering. Nevertheless, existing methods cannot model the differential contribution of atoms in various regions of proteins, and the relationship between atom properties and intermolecular distance is also not fully explored. We propose a novel empirical graph neural network for accurate protein-ligand binding affinity prediction (EGNA). Graphs of protein, ligand and their interactions are constructed based on different regions of each bound complex. Proteins and ligands are effectively represented by graph convolutional layers, enabling the EGNA to capture interaction patterns precisely by simulating empirical SFs. The contributions of different factors on binding affinity can thus be transparently investigated. EGNA is compared with the state-of-the-art machine learning-based SFs on two widely used benchmark data sets. The results demonstrate the superiority of EGNA and its good generalization capability.

CO2 Dipole Moment: A Simple Model and Its Implications for CO2-Rock Interactions

CO2 is a widespread fluid naturally occurring within the Earth crust or injected in deep strata for technological issues such as Carbon Capture and Storage (CCS). At STP conditions, CO2 is a gas, with a net zero dipole moment. Growing pressures produce an increase in its density. The reduced intermolecular distance causes a variation in the molecular structure, due to the intensification of mutual interactions. Some published spot data reveal the departure from the planarity of the bond angle while others provide few values of the CO2 dipole moment. Based on a small amount of literature-measured angle values, it was possible first to extrapolate a correlation between bond angle and density (R2 = 0.879). By fixing the partial charges distribution, we present a simple model that allows the calculation of the CO2 dipole moment directly from the geometry of the molecule, in the range of 179–162 degrees, 1-degree step. Results give values up to about 1 D. Being aware that this model is qualitative, it gives, however, an explanation of the experimental reactivity, and it also provides a valid tool in identifying zones in the crust where these reactions are likely to occur efficiently. Finally, we hypothesise the role of dry CO2 in the carbonate formation through the interactions with the basalts.

Spectroscopic investigation of energy transfer from composition dependent ternary QDs to hemicyanine dye

Systematic spectroscopic investigation of fluorescence (Förster) resonance energy transfer (FRET) is performed for a pair of ternary quantum dots (TQDs) CdSeS/ZnS with LDS698 dye. Composition of TQDs plays an important role in tuning emission wavelength keeping the size same. Coupling of-COOH functionalized QDs with dye results in decreasing fluorescence intensity and lifetimes of QDs analogous to quenching mechanism. The observed enhancement in acceptor intensity is essentially due to dipole–dipole interaction confirming energy transfer and its dependence on spectral overlap. FRET parameters like spectral overlap, Förster’s distance, intermolecular distance, etc., are calculated. The results strongly suggest that the chosen FRET pairs find potential application in bio-imaging and targeted drug delivery.

A supramolecular assembly-based strategy towards the generation and amplification of photon up-conversion and circularly polarized luminescence.

For the molecular properties in which energy transfer/migration is determinantal, such as triplet-triplet annihilation-based photon up-conversion (TTAUC), the overall performance is largely affected by the intermolecular distance and relative molecular orientations. In such scenarios, tools that may steer the intermolecular interactions and provide control over molecular organisation in the bulk, become most valuable. Often these non-covalent interactions, found predominantly in supramolecular assemblies, enable pre-programming of the molecular network in the assembled structures. In other words, by employing supramolecular chemistry principles, an arrangement where molecular units are arranged in a desired fashion, very much like a Lego toy, could be achieved. This leads to enhanced energy transfer from one molecule to other. In recent past, chiral luminescent systems have attracted huge attention for producing circularly polarized luminescence (CPL). In such systems, chirality is a necessary requirement. Chirality induction/transfer through supramolecular interactions has been known for a long time. It was realized recently that it may help in the generation and amplification of CPL signals as well. In this review article we have discussed the applicability of self-/co-assembly processes for achieving maximum TTA-UC and CPL in various molecular systems.

Investigations on optical and photoluminescence properties of Dy3+ doped zinc tellurite glass

• The structural, thermal and optical properties of the Dy 3+ doped tellurite (TZND) glass system were investigated. • Properties of samples were measured and described in the current study using XRD, SEM, and EDS methods. • The forbidden energy gap values for the direct and indirect transitions are found between 2.98 and 3.02 eV and 2.90–2.94 eV respectively. • The effects of Dy 3+ ion on absorption and photoluminescence spectra were studied. • The TZND glasses doped with Dy 3+ ion have potential to be the best photonic and light emitting host material. Zinc-sodium-tellurite glasses doped with Dy 3+ (TZND) with the chemical compositions (70-x) %TeO 2 –20 %ZnO–10 %Na 2 O-x%Dy 2 O 3 (where × is 0, 0.5 and 1 in mol%) were synthesize by traditional melt-quenching method. The samples were characterized using X-ray diffraction, SEM-EDS, optical absorption and PL spectra. Differential scanning calorimetry (DSC) was carried to determine the glass transition temperature of synthesized samples. The non-crystalline nature of TZND samples was confirmed by XRD measurements and compositions were verified by EDS. Raman spectra have been carried to characterize the architectural attributes of glass matrices. Other parameters of prepared samples as density(ρ), molar volume (V m ), polaron radius R p , oxygen packing density and intermolecular distance R i were calculated. The optical band gap, refractive index (n), cut-off wavelength, and the Urbach's energy were determined from the absorption spectra. The PL spectra for upconversion characteristics indicate two intense bands due to 4 F 9/2 → 6 H 15/2 (around 480 nm) and 4 F 9/2 → 6 H 13/2 (around 570 nm) transitions respectively.

Spin-orbit coupling in molecular complexes beyond van der Waals regime: Key factors for further splitting of 2P3/2 ground state

We report a joint spectroscopic and theoretical study probing spin-orbit coupling (SOC) in a variety of molecular complexes between an iodine atom and a ligand (L) with L ranging from Ar, HF to formic/acetic acids, and glycine/N-methylated glycine derivatives. Cryogenic photoelectron spectroscopy of L·I- (L=HCOOH, CH3COOH) reveals three distinct peaks, identified as three SOC states, denoted as X(1/2), A(3/2), and B(l/2) for the corresponding neutrals. The X and A separation ΔEXA is measured to be 0.10 eV for both, whereas the X and B gap ΔEXB is 0.98 and 0.97 eV for formic and acetic acid, respectively. These new ΔEXA values are compared with the previously reported values for the molecular complexes L·I· with L=Ar, HF, glycine, and A-methylated glycines. All together these complexes encompass a diversity of intermolecular interactions, from van der Waals to weak and strong hydrogen bonding. While the ΔEXB remains similar, the ΔEXA is shown to be extremely sensitive to the type of ligands and interactions, spanning from 5 meV to 150 meV. High-level relativistic quantum calculations including explicit SOC formulism nicely reproduce all experimental SOC splitting. A direct correlation between the magnitude of ΔEXA with the intermolecular interaction strength or bond distance of the neutral complexes—the stronger interaction (shorter bond length), the greater splitting, is established.

Quadrature-based lattice Boltzmann model for non-equilibrium dense gas flows

The Boltzmann equation becomes invalid as the size of gas molecules is comparable with the average intermolecular distance. A better description is provided by the Enskog collision operator, which takes into account the finite size of gas molecules. This extension implies nonlocal collisions as well as an increase in collision frequency, making it computationally expensive to solve. An approximation of the Enskog collision operator, denoted the simplified Enskog collision operator, is used in this work to develop a quadrature-based lattice Boltzmann model for non-ideal monatomic dense gases. The Shakhov collision term is implemented in order to fine-tune the Prandtl number. This kinetic model is shown to be able to tackle non-equilibrium flow problems of dense gases, namely, the sound wave and the shock wave propagation. The results are compared systematically with the results of the more accurate but computationally intensive particle method of solving the Enskog equation. The model introduced in this paper is shown to have good accuracy for small to moderate denseness of the fluid (defined as the ratio of the molecular diameter to the mean free path), and due to the efficiency in terms of computational time, it is suitable for practical applications.

Photoassociation spectra of cesium 31D<sub>5/2</sub>+6S<sub>1/2</sub>(<i>F</i> = 4) ultralong-range Rydberg molecules

In this paper, we conduct the experiment and simulation on 31D<sub>5/2</sub>+6S<sub>1/2</sub>(<i>F</i> = 4) Cs<sub>2</sub> ultralong-range Rydberg molecules (ULRMs). These molecules are prepared by employing a two-photon photoassociation scheme. Two distinct ultralong-range Rydberg molecular signals are observed at the detuning –162.8 MHz and –66.6 MHz of 31D<sub>5/2</sub> atomic resonant line, which are bound by the pure triplet potential and mixed singlet-triplet potential, respectively. We use the model of scattering interaction between the Rydberg electron and ground-state atom to perform the simulation. The molecular potential-energy curves are obtained by solving the Hamiltonian on a grid of intermolecular distances <i>R</i>. The calculations of the binding energy of pure triplet and mixed singlet-triplet <i>v</i> = 0 vibrational states are compared with the experimental measurements. The calculated and measured values of the binding energy are in good agreement. The s-wave pure triplet and singlet zero-energy scattering length are obtained to be <inline-formula><tex-math id="M3">\begin{document}${a}_{{\rm{s}}}^{{\rm{T}}}({0})=-{19.16}{a}_{0}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230520_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230520_M3.png"/></alternatives></inline-formula> and <inline-formula><tex-math id="M4">\begin{document}$ {a}_{{\rm{s}}}^{{\rm{S}}}(0)=-{1.92}{a}_{0} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230520_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230520_M4.png"/></alternatives></inline-formula>, respectively. This kind of molecule with large size, abundant vibrational states and large permanent electric dipole moment is an excellent candidate for studying low-energy collision dynamics. The study of these molecules will further deepen and enrich the understanding of the special binding mechanism and exotic properties of the ULRMs.

On the antiaromatic-aromatic-antiaromatic transition of the stacked cyclobutadiene dimer.

We have studied the changes in the aromatic nature of two cyclobutadiene (C4H4) molecules on decreasing the intermolecular distance and approaching the cubane structure in a face-to-face fashion. The analysis based on the calculations of the magnetically induced current density and the induced magnetic field shows that the aromaticity of the two C4H4 rings changes from a strongly antiaromatic character at long distances to an aromatic transition state of stacked C4H4 rings at intermediate internuclear distances when approaching the antiaromatic state of cubane.

19F electron nuclear double resonance (ENDOR) spectroscopy for distance measurements using trityl spin labels in DNA duplexes.

The combination of fluorine labeling and pulsed electron-nuclear double resonance (ENDOR) is emerging as a powerful technique for obtaining structural information about proteins and nucleic acids. In this work, we explored the capability of Mims 19F ENDOR experiments on reporting intermolecular distances in trityl- and 19F-labeled DNA duplexes at three electron paramagnetic resonance (EPR) frequencies (34, 94, and 263 GHz). For spin labeling, we used the hydrophobic Finland trityl radical and hydrophilic OX063 trityl radical. Fluorine labels were introduced into two positions of a DNA oligonucleotide. The results indicated that hyperfine splittings visible in the ENDOR spectra are consistent with the most populated interspin distances between 19F and the trityl radical predicted from molecular dynamic (MD) simulations. Moreover, for some cases, ENDOR spectral simulations based on MD results were able to reproduce the conformational distribution reflected in the experimental ENDOR line broadening. Additionally, MD simulations provided more detailed information about the melting of terminal base pairs of the oligonucleotides and about the configuration of the trityls relative to a DNA end.

Singlet fission preserves polarisation correlation of excitons.

Singlet fission (SF) holds the promise to circumvent the photovoltaic efficiency limit to reach a power-conversion efficiency above 34%. SF of TIPS-pentacene (TIPS-Pn) has been investigated but its mechanism is yet to be well elucidated. Recently, we developed a nanoparticle (NP) system, in which doping of TIPS-Pn in a host matrix yields a range of average intermolecular distances, d, to study the dependence of SF in TIPS-Pn on d. At large d values, where the bimolecular SF process should be unfavourable, a relatively high SF quantum yield (ΦSF) is still observed, which implies a deviation from a random distribution of TIPS-Pn throughout the NP. Here, using polarisation-sensitive femtosecond time-resolved spectroscopy and Monte Carlo simulations of exciton migration and SF, we quantify the level of clustering of TIPS-Pn in the host matrix, which is responsible for the higher than expected ΦSF. The experimental data indicate a preservation of polarisation correlation by SF, which is uncommon because energy transfer in amorphous materials tends to result in depolarisation. We show that the preservation of polarisation correlation is due to SF upon exciton migration. Although exciton migration decorrelates polarisation, SF acts to remove decorrelated excitons to give an overall preservation of polarisation correlation.

Insight into the effect of biaxial compression strain on adsorption structure of bituminous coal matrix as well as gas diffusion and permeability properties by macromolecule simulation

The concentrated stress induced by mining activities leads to deformation of the coal, especially the coal matrix, which affects the production of coalbed methane (CBM). Therefore, grand canonical Monte Carlo and molecular dynamics methods were used to study the effect of biaxial compression strain on the adsorption structure of the bituminous coal matrix as well as the CH4/CO2/N2 diffusion and permeability properties based on the constructed macromolecular coal model. The results show that the dual-mode equation fits the gas adsorption isotherm and the order of influence of adsorption concentration on the model structure is N2 > CO2 > CH4. For the diffusion models, the orders of swelling rate and specific volume are CH4 > N2 > CO2, while those of the fractional free volume and pore volume are opposite. Compression (negative) strain (0.00 ∼ −0.20) reduces the bulk modulus but has a negligible effect on the shear modulus and wave velocity. Also the Poisson’s ratio of the CH4 diffusion model is smaller compared to the CO2/N2 diffusion model. The cohesive energy density (CED) order is CO2 > N2 > CH4 and its van der Waals component accounts for the major part. The mean square displacement distribution of gases successively increases in the power function and linearity with time. The self-diffusion coefficient of CH4 is larger than that of CO2/N2, which is greatly affected by strain. The (negative) interaction energy order between gas and coal matrix is CH4 > N2 > CO2, and the order of intermolecular interaction distance of gases is N2 > CO2 > CH4. Most importantly, the solubility order of gases is CO2 > CH4 > N2, and the strain has the dual effect of promoting and inhibiting the permeability of the coal matrix. The research results provide molecular-level insights into CBM recoveries in coal reservoirs with different strain degrees, with some technical value and theoretical importance.