Accurate and Efficient Schemes for Mapping Out Two Isolated Seams of Conical Intersections with Neural Networks Solely Based on Adiabatic Energies: A Case Study of H + NO(Π) → H + NO(Σ).

A new scheme in the neural network (NN) diabatization approach that solely utilizes the adiabatic energies for constructing the global diabatic potential energy matrices (PEMs) of the molecular systems with two isolated seams of conical intersections (CIs) is proposed. Taking a prototype charge transfer reaction H + NO(Π) → H + NO(Σ), where two seams of CIs are located at the different linear geometries N-O-H and O-N-H, for example, the diabatization with the new scheme including a diabatic state constraint is shown to map out the topographies of both two linear CIs with 100% of the success rate in 10 different trainings, while the diabatization without such constraint hardly represents CIs, in which the avoided crossings appear instead. Simultaneously, we propose a scheme to separate the whole reactive space into three different regions and define the minimal Euclidean distances for each region to efficiently sample the energy points for the NN trainings.

Neural network potentials facilitating accurate complex scaling for molecular resonances: from a model to high dimensional realistic systems.

Here we propose a neural network based complex scaling (NN-CS) method for computing the complex eigenvalues (-/2) of molecular resonances, in which the CS of the potential part in the non-Hermitian Hamiltonian is effectively achieved by NNs. Taking a two-dimensional (2D) diabatic model including two states coupled by the conical intersection for example, the NN-CS method is shown to reproduce the eigenvalues of the resonance states quite well. Subsequently, this NN-CS method with a 2D Hamiltonian model is utilized to compute the vibronic resonances in the nσ*-mediated photodissociation of thioanisole based on a new NN diabatic potential energy matrix.

Bacterial Susceptibility to Ceria Nanoparticles: The Critical Role of Surrounding Molecules.

Investigating the ternary relationship among nanoparticles (NPs), their immediate molecular environment, and test organisms rather than the direct interaction between pristine NPs and test organisms has been thrust into the mainstream of nanotoxicological research. Diverging from previous work that predominantly centered on surrounding molecules affecting the toxicity of NPs by modulating their nanoproperties, this study has unveiled a novel dimension: surrounding molecules altering bacterial susceptibility to NPs, consequently impacting the outcomes of nanobio interaction. The study found that adding nitrate as the surrounding molecules could alter bacterial respiratory pathways, resulting in an enhanced reduction of ceria NPs (nanoceria) on the bacterial surfaces.

Computational determination of the S1(Ã1A″) absorption spectra of HONO and DONO using full-dimensional neural network potential energy surfaces.

The Ã1A″ ← X̃1A' absorption spectra of HONO and DONO were simulated by a full six-dimensional quantum mechanical method based on the newly constructed potential energy surfaces for the ground and excited electronic states, which were represented by the neural network method utilizing over 36 000 ab initio energy points calculated at the multireference configuration interaction level with Davidson correction. The absorption spectrum of HONO/DONO comprises a superposition of the spectra from two isomers, namely, trans- and cis-HONO/DONO, due to their coexistence in the ground X̃1A' state. Our calculated spectra of both HONO and DONO were found to be in fairly good agreement with the experiment, including the energy positions and widths of the peaks.

Impact of Geometric Phase on Dynamics of Complex-Forming Reactions: H + O → OH + O.

Reaction dynamics on the ground electronic state might be significantly influenced by conical intersections (CIs) via the geometric phase (GP), as demonstrated for activated reactions (i.e., the H + H exchange reaction).

Quantum state-to-state nonadiabatic dynamics of the charge transfer reaction H+ + NO(X2Π) → H + NO+(X1Σ+): Influence of ro-vibrational excitation of NO.

Quantum state-to-state nonadiabatic dynamics of the charge transfer reaction H+ + NO(X2Π, vi = 1, 3, ji = 0, 1) → H + NO+(X1Σ+) has been studied based on the recently constructed diabatic potential energy matrix. It was found that the vibrational excitation of reactant NO inhibits the reactivity, while the rotational excitation of reactant NO has little effect on the reaction probability. These attributes were also observed in the semi-classical trajectory calculations employed in the adiabatic representation.

Quantum Dynamics of Photodissociation: Recent Advances and Challenges.

Recent advances in constructing accurate potential energy surfaces and nonadiabatic couplings from high-level data have revealed detailed potential landscapes in not only the ground electronic state but also excited ones. They enabled quantitatively accurate characterization of photoexcited reactive systems using quantum mechanical methods. In this Perspective, we survey the recent progress in quantum mechanical studies of adiabatic and nonadiabatic photodissociation dynamics, focusing on initial state control and product energy disposal.

Full-dimensional potential energy surface for the photodissociation of HNCO its S band.

A full-dimensional potential energy surface (PES) for the first excited state S(A'') of HNCO has been built up by the neural network method based on more than 36 000 points, which were calculated at the multireference configuration interaction level with Davidson correction using the augmented correlation consistent polarized valence triple zeta basis set. It was found that two minima, namely, and isomers of HNCO, and another seven stationary points exist on the S PES for the two dissociation pathways: HNCO(S) → H + NCO/NH + CO. Particularly, a new out-of-plane transition state between the two minima was found in this work, thanks to including all the degree of freedoms for this system.

Advanced nanopesticides: Advantage and action mechanisms.

The use of various chemical substances to control pests, diseases, and weeds in the field is a necessary part of the agricultural development process in every country. While the application of pesticides can improve the quality and yield of crops, plant resistance and the harm caused by pesticide residues to the environment and humans have led to the search for greener and safer pesticide formulations to improve the current situation. In recent years, nanopesticides (NPts) have shown great potential in agriculture due to their high efficiency, low toxicity, targeting, resistance, and controlled slow release demonstrated in the experimental stage.

Toward a Unified Analytical Description of Internal Conversion and Intersystem Crossing in the Photodissociation of Thioformaldehyde. I. Diabatic Singlet States.

The photodissociation of thioformaldehyde is an archetypal system for the study of competition between internal conversion and intersystem crossing, which involves its two singlet states (S and S) and two triplet states (T and T). In order to perform accurate dynamic simulations, either quantum or quasi-classical, it is essential to construct an analytical representation for all necessary electronic structure data. In this work, a diabatic potential energy matrix (DPEM), , for the two singlet states (S and S) is reported.

Nonadiabatic quantum dynamics of the charge transfer reaction H + NO(XΠ) → H + NO(XΣ).

Nonadiabatic quantum dynamics of the charge transfer (CT) reaction H + NO(XΠ) → H + NO(XΣ) is investigated on a new diabatic potential energy matrix (PEM) including the 1A' and 2A' states of HNO/HON at the multireference configuration interaction level with Davidson correction using a large basis set. The diabatization of the two coupled states was achieved by the adiabatic-to-diabatic transformation with a mixing angle and the final diabatic PEM was obtained by fitting each matrix element separately using a three-dimensional cubic spline interpolation including more than 22 000 points. The reaction was found to be dominated by the resonances supported by the double well associated with HNO and HON species, manifested by the oscillatory structures in the reaction probabilities and product rotational distributions.

Simulating the HeI photoelectron spectrum of ClO with new full-dimensional adiabatic potential energy surfaces of ClO(X̃A), ClO(X̃B), and ClO(C̃A) and a three-state diabatic potential energy matrix of ClO(ÃB, B̃A, and 2A): a quantum mechanical study.

To interpret the HeI photoelectron spectrum of ClO (involving four lowest electronic states of ClO), in this work we first constructed the associated adiabatic full-dimensional potential energy surfaces (PESs) of ClO(X̃A), ClO(X̃B), and ClO(C̃A) and a diabatic potential energy matrix (PEM) of ClO(AB, B̃A, and 2A) using the explicitly correlated internally contracted multi-reference configurational interaction with Davidson correction (MRCI-F12+Q) and neural network methods. Particularly for the AB, B̃A, and 2A states of ClO coupled in terms of conical intersection, their diabatization is achieved by the neural network approach based merely on the associated adiabatic energies. With the help of newly constructed adiabatic PESs and the diabatic PEM, the HeI photoelectron spectrum of ClO is further computed quantum mechanically.

Nonadiabatic heavy atom tunneling in nσ*-mediated photodissociation of thioanisole.

The nσ*-mediated photodissociation dynamics of thioanisole is investigated quantum mechanically using a three-dimensional model based on a newly constructed diabatic potential energy matrix. The lifetimes of the low-lying S(ππ*) resonances are determined and found to accord well with available experimental data. Specifically, our theoretical results demonstrate that the photodissociation of thioanisole at the low-lying S(ππ*) levels takes place the heavy atom tunneling due to the higher S/S conical intersection and two equivalent out-of-plane saddle points appearing on the dissociation path.

Constructing Diabatic Potential Energy Matrices with Neural Networks Based on Adiabatic Energies and Physical Considerations: Toward Quantum Dynamic Accuracy.

A permutation invariant polynomial-neural network (PIP-NN) approach for constructing the global diabatic potential energy matrices (PEMs) of the coupled states of molecules is proposed. Specifically, the diabatization scheme is based merely on the adiabatic energy data of the system, which is ideally a most convenient way due to not requiring additional calculations for the data of the derivative coupling or any other physical properties of the molecule. Considering the permutation and coupling characteristics of the system, particularly in the presence of conical intersections, some vital treatments for the off-diagonal terms in diabatic PEM are essentially needed.

Geometric Phase Effect in Attosecond Stimulated X-ray Raman Spectroscopy.

Conical intersections (CIs) are diabolical points in the potential energy surfaces generally caused by point-wise degeneracy of different electronic states, and give rise to the geometric phases (GPs) of molecular wave functions. Here we theoretically propose and demonstrate that the transient redistribution of ultrafast electronic coherence in attosecond Raman signal (TRUECARS) spectroscopy is capable of detecting the GP effect in excited state molecules by applying two probe pulses including an attosecond and a femtosecond X-ray pulse. The mechanism is based on a set of symmetry selection rules in the presence of nontrivial GPs.

Defining the Surface Oxygen Threshold That Switches the Interaction Mode of Graphene Oxide with Bacteria.

As antimicrobials, graphene materials (GMs) may have advantages over traditional antibiotics due to their physical mechanisms of action which ensure less chance of development of microbial resistance. However, the fundamental question as to whether the antibacterial mechanism of GMs originates from parallel interaction or perpendicular interaction, or from a combination of these, remains poorly understood. Here, we show both experimentally and theoretically that GMs with high surface oxygen content (SOC) predominantly attach in parallel to the bacterial cell surface when in the suspension phase.

Ultrahigh extinction ratio and ultralow insertion loss for polarization beam splitter based on two folded asymmetrical directional couplers with dual-stage etching.

We propose and experimentally demonstrate a polarization beam splitter (PBS) with excellent performance in terms of ultrahigh extinction ratio and ultralow insertion loss. The PBS consists of two dual-stage etched asymmetrical directional couplers, which are cascaded by a bend waveguide to form a folded structure. In the PBS, the fundamental transverse magnetic ( ) mode is efficiently cross-coupled to the cross-port, while the fundamental transverse electric ( ) mode outputs at the through-port.

Characterization of the lipidomic profile of clam Meretrix petechialis in response to Vibrio parahaemolyticus infection.

Vibrio parahaemolyticus is a devastating pathogen of clam Meretrix petechialis, which brings about huge economic losses in aquaculture breeding industry. In our previous study, we have found that Vibrio infection is closely associated with lipid metabolism of clams. In this study, an untargeted lipidomics approach was used to explore the lipid profiling changes upon Vibrio infection.

From marine to freshwater environment: A review of the ecotoxicological effects of microplastics.

Microplastics (MPs) have been widely detected in the world's water, which may pose a significant threat to the ecosystem as a whole and have been a subject of much attention because their presence impacts seas, lakes, rivers, and even the Polar Regions. There have been numerous studies that report direct adverse effects on marine organisms, but only a few have explored their ecological effects on freshwater organisms. In this field, there is still a lack of a systematic overview of the toxic effects and mechanisms of MPs on aquatic organisms, as well as a consistent understanding of the potential ecological consequences.

Graphene oxide disruption of homeostasis and regeneration processes in freshwater planarian Dugesia japonica via intracellular redox deviation and apoptosis.

The aquatic system is a major sink for engineered nanomaterials released into the environment. Here, we assessed the toxicity of graphene oxide (GO) using the freshwater planarian Dugesia japonica, an invertebrate model that has been widely used for studying the effects of toxins on tissue regeneration and neuronal development. GO not only impaired the growth of normal (homeostatic) worms, but also inhibited the regeneration processes of regenerating (amputated) worms, with LC values of 9.

Toxicity of ceria nanoparticles to the regeneration of freshwater planarian Dugesia japonica: The role of biotransformation.

Cerium oxide nanoparticles (n-CeO) have wide applications ranging from industrial to consumer products, which would inevitably lead to their release into the environment. Despite the toxicity of n-CeO on aquatic organisms has been largely reported, research on developing organisms is still lacking. In this study, we investigate the toxic effects of n-CeO on the stem cells, tissue- and neuro-regeneration, using freshwater planarian Dugesia japonica as a model.

Sodium Benzoate Delays the Development of Larvae and Alters Commensal Microbiota in Adult Flies.

Sodium benzoate (SB), the sodium salt of benzoic acid, is widely used as a preservative in foods and drinks. The toxicity of SB to the human body attracted people's attention due to the excessive use of preservatives and the increased consumption of processed and fast foods in modern society. The SB can inhibit the growth of bacteria, fungi, and yeast.

Quantum resonances and roaming dynamics in formaldehyde photodissociation.

The unimolecular dissociation of formaldehyde is studied excitation to the à band at several excitation energies from just below the ground state radical dissociation threshold to 5000 cm above it. CO product rotational distributions, photofragment excitation spectroscopy and state-correlated slice imaging results are combined with quasi-classical trajectory calculations to reveal manifestations of quantum effects in this complex dissociation process involving interactions among radical, molecular, and roaming pathways. Evidence of nodal structure at the tight transition state to molecular products is investigated and correlations between the CO rotational and H vibrational distributions are used to suggest the transition state modes that are responsible.

Effects of ceria nanoparticles and CeCl on growth, physiological and biochemical parameters of corn (Zea mays) plants grown in soil.

The release of toxic ions from metal-based nanoparticles (NPs) may play an important role in biological effects of NPs. In this life cycle study, physiological and biochemical responses of soil-grown corn (Zea mays) plants exposed to ceria NPs and its ionic counterparts Ce ions at 0, 25, 75 and 225 mg Ce/kg were investigated. Both treatments tended to reduce the fresh weight and height of the plants at 28 days after sowing (DAS), and delay silk appearance and finally decrease fruit weight at harvest.

Effect of CeO nanoparticles on plant growth and soil microcosm in a soil-plant interactive system.

The impact of CeO nanoparticles (NPs) on plant physiology and soil microcosm and the underlying mechanism remains unclear to date. This study investigates the effect of CeO NPs on plant growth and soil microbial communities in both the rhizosphere of cucumber seedlings and the surrounding bulk soil, with CeCl as a comparison to identify the contribution of the particulate and ionic form to the phytotoxicity of CeO NPs. The results show that Ce was significantly accumulated in the cucumber tissue after CeO NPs exposure.