In this work, we have investigated the electronic properties of the pristine and metal(M)-doped Si12C12 (M = Sc, V, Ti, Fe and Mn) nanocages and their sensing performances towards the penicillamine (PCE) molecule using DFT calculations at the B3LYP/LanL2DZ/6-311G(d,p) method. The results reveal that the doping of the Si12C12 nanocage with a metal atom significantly improves its reactivity, therefore their interaction with the nucleophilic centres of the PCE molecule becomes easy. The most stable complexes were obtained when the PCE molecule was chemisorbed onto the MSi12C12 nanocages through its oxygen atom with adsorption energies which vary from –18.0 to –40.2 kcal mol−1. The results also demonstrate that the MSi12C12 possess high sensitivity towards the PCE molecule. The presence of solvent sharply reduces the adsorption energy of the PCE molecule over the clusters surface, resulting in a substantial decrease in the recovery time. A comparative study between the values of the sensitivity of the studied clusters in liquid phase suggests that the FeSi12C12 and MnSi12C12 clusters present high sensing performances compared with the other clusters, so they are regarded as the best sensors to detect the PCE drug molecule.

In this work, we investigate an ion-atom model describing the time-dependent evolution of electron density during the collision. For a S 3 + − H system, numerical simulations are based on classical trajectory calculations, and the electron density behaviour is described with the time-dependent Schrödinger equation. We apply the finite difference method to obtain quantitative insights into the charge transfer dynamics, providing detailed information about the spatial and temporal evolution of the collision process. The results are given for representative examples of the collision, from eV to keV range of energies, in head-on collision as well as for different values of impact parameter. A validity and precision of the proposed model and interpretation of the particle collision in terms of eigenstates are also discussed.

Many stochastic processes in the physical and biological sciences can be modelled as Brownian dynamics with multiplicative noise. However, numerical integrators for these processes can lose accuracy or even fail to converge when the diffusion term is configuration-dependent. One remedy is to construct a transform to a constant-diffusion process and sample the transformed process instead. In this work, we explain how coordinate-based and time-rescaling-based transforms can be used either individually or in combination to map a general class of variable-diffusion Brownian motion processes into constant-diffusion ones. The transforms are invertible, thus allowing recovery of the original dynamics. We motivate our methodology using examples in one dimension before then considering multivariate diffusion processes. We illustrate the benefits of the transforms through numerical simulations, demonstrating how the right combination of integrator and transform can improve computational efficiency and the order of convergence to the invariant distribution. Notably, the transforms that we derive are applicable to a class of multibody, anisotropic Stokes-Einstein diffusion that has applications in biophysical modelling.

In this investigation, we employ density functional theory (DFT) with the generalised gradient approximation of Perdew–Burke–Ernzerhof (GGA-PBE) and the modified Beck-Johnson approach (mBJ-GGA). Our focus is on examining the optoelectronic and thermoelectric properties of Bi4Fe2Hf4Pt2 and Sb4Fe2Hf4Pt2 compounds. The findings indicate that both compounds are stable in non-magnetic phase (NM). Regarding electronic characteristics, it is revealed that these compounds are direct bandgap semiconductors. The optical analysis suggests that these compounds demonstrate high reflectivity within the visible and ultraviolet spectra, rendering them promising candidates for solar cells and photovoltaic applications. Furthermore, these materials present as highly promising candidates for thermoelectric purposes due to their remarkable figure of merit (ZT) and notable Seebeck coefficient (S) values. However, there is a lack of theoretical or experimental data available for these compounds for conducting comparison with our results. We think future experimenters attempting to synthesise these chemicals experimentally will benefit from the current study.

Amino acids are essential for Earth-like life and are hypothesised to have originated in interstellar space, potentially being transported to Earth via meteorite impacts. Detecting amino acids in interstellar environments and understanding their formation mechanisms through laboratory experiments are crucial for supporting this hypothesis and unravelling the origins of life. In this study, the formation of serine ( NH 2 CH ( CH 2 OH ) COOH ) from α-glycyl ( NH 2 C ⋅ HCOOH ) and hydroxymethyl ( ⋅ CH 2 OH ) radicals was investigated using quantum chemical computations. It was found that the anticipated recombination reaction, along with analogous formation pathways of other natural amino acids, is accompanied by competing reactions yielding alternative products, potentially diminishing serine formation. Alternative interstellar formation pathways for serine are proposed, which could be experimentally tested by future laboratory studies.

We describe the development of machine-learned (ML) potentials for flexible, weakly interacting monomers. A recently suggested permutationally invariant polynomial neural network (PIP-NN) approach is utilised to represent the full-dimensional two-body component of the molecular pair energy. To ensure the asymptotic zero-interaction limit, a tailored subset of the full invariant polynomial basis set is utilised, and their variables are modified to achieve a better fit of the correct asymptotic behaviour at a long range. This new technique is used to build full-dimensional potentials for the two-body N 2 –Ar and N 2 –CH 4 interactions by fitting databases of ab initio energies calculated at the coupled-cluster level of theory. The second virial coefficient, fully accounting for molecular flexibility, is then calculated within the classical framework using the obtained PIP-NN potential surfaces. A trajectory-based simulation of the N 2 –Ar collision-induced absorption is conducted, covering both the far- and mid-infrared ranges.

The excited state intramolecular proton transfer (ESIPT) reaction is a well-studied photo reaction, based on this mechanism, many high-performance organic chromophores can be selected. It is widely acknowledged that the 2-(2’-hydroxyphenyl)benzazole (HBX) derivatives undergo the ESIPT process. This work mainly uses DFT and TDDFT methods to clarify the effects of oxygen family substituted elements on excited states for HBX derivatives. First, we probe into the molecular structures of HBX derivatives (HBX-O, HBX-S and HBX-Se) and explore their infrared (IR) vibrational behaviours. The results confirm that light excitation in S1 state enhances the hydrogen bonds of HBX dyes. Additionally, analysis of the frontier molecular orbitals shows that charge redistribution promotes the ESIPT process. This article provides a detailed explanation of the excited state reaction behaviours of three HBX dyes and demonstrates that substitution effects regulate the ESIPT processes of these dyes. This finding will contribute to the development of new photo-reactive substances in the future.

Various condensed phases of water, spanning from the liquid state to multiple ice phases, have been systematically investigated under extreme conditions of pressure and temperature to delineate their stability boundaries. This study focuses on probing the mechanical stability of liquid water through path-integral molecular dynamics simulations, employing the q-TIP4P/F potential to model interatomic interactions in flexible water molecules. Temperature and pressure conditions ranging from 250 to 375 K and − 0.3 to 1 GPa, respectively, are considered. This comprehensive approach enables a thorough exploration of nuclear quantum effects on various physical properties of water through direct comparisons with classical molecular dynamics results employing the same potential model. Key properties such as molar volume, intramolecular bond length, H–O–H angle, internal and kinetic energy are analysed, with a specific focus on the effect of tensile stress. Particular attention is devoted to the liquid-gas spinodal pressure, representing the limit of mechanical stability for the liquid phase, at several temperatures. The quantum simulations reveal a spinodal pressure for water of − 286 and − 236  MPa at temperatures of 250 and 300 K, respectively. At these temperatures, the discernible shifts induced by nuclear quantum motion are quantified at 15 and 10 MPa, respectively. These findings contribute valuable insights into the interplay of quantum effects on the stability of liquid water under diverse thermodynamic conditions.

In this theoretical study, we have conducted calculations to investigate the pressure broadening of the H ( 4 s 2 S 1 / 2 − 4 p 2 P 1 / 2 ) and the K ( 4 s 2 S 1 / 2 − 4 p 2 P 3 / 2 ) lines of the Ca + calcium ion in a gas of ground-state He helium atoms. The focus of our work is to determine the profiles of the pressure-broadened resonance lines and analyse their behaviour under the influence of binary collisions between Ca + ions and He atoms. To achieve this, we constructed accurate potential energy curves for the ground X 2 Σ 1 / 2 + and the excited D 2 Π 1 / 2 , D 2 Π 3 / 2 and E 2 Σ 1 / 2 + states. Additionally, we constructed the corresponding transition dipole moments based on the data obtained through high-level ab initio methods, including SA-CASSCF, MRCI, and SO coupling, with Davidson and BSSE corrections. The study spans a range of temperatures from 4000 K to 12,000 K and wavelengths from 200 nm to 500 nm . The theoretical profile is characterised by dominant free-free transitions. In the vicinity of the 436 nm wavelength position, there is a satellite peak in the red wing, attributed to the contribution of D 2 Π 1 / 2 ⟵ X 2 Σ 1 / 2 + and D 2 Π 3 / 2 ⟵ X 2 Σ 1 / 2 + transitions. Our findings are in good agreement with previous theoretical results.

Recently, after initial rectification, adsorption has become a viable method for further purification of SiHCl3, but much work remains to be done to find a suitable adsorbent. Quantum chemical calculations offers a feasible way to study the mechanism of adsorption, which help develop appropriate adsorbents. Aromatic amines are widely used as adsorbents for BCl3 in SiHCl3, but the adsorption mechanism remains unclear, which impedes the development of efficient adsorbents. In this work, density functional theory is used to investigate the adsorption configuration, adsorption energy and electronic properties of BCl3-SiHCl3 on aromatic amines and the mechanism of interaction between BCl3/SiHCl3 and aromatic amines is analyzed and discussed. The results show that BCl3/SiHCl3 could achieve the separation criteria after two-stage adsorption using aromatic amines (except diphenylamine and triphenylamine) as adsorbent. The adsorption performance decreases as the hydrogen on the nitrogen is gradually replaced by the aromatic ring. When the hydrogen on the benzene ring is substituted with methyl, the adsorption performance of adsorbents changes, which is also position specific. The adsorption energy (-30.63kJ/mol) of p-methylaniline for BCl3 is the highest at 298 K and 1atm. Besides, the desorption behavior of aromatic amines on BCl3 is investigated by increasing the temperature and lowering the pressure by evacuation, and it is found that varying pressure is less energy intensive than increasing the temperature. A combination of adsorption capacity and desorption degree considerations suggest that aromatic amines can be used as adsorbent materials.