A generalized exchange-correlation functional: the Neural-Networks approach

A Neural-Networks-based approach is proposed to construct a new type of exchange-correlation functional for density functional theory. It is applied to improve B3LYP functional by taking into account of high-order contributions to the exchange-correlation functional. The improved B3LYP functional is based on a neural network whose structure and synaptic weights are determined from 116 known experimental atomization energies, ionization potentials, proton affinities or total atomic energies which were used by Becke in his pioneer work on the hybrid functionals [J. Chem. Phys. ${\bf 98}$, 5648 (1993)]. It leads to better agreement between the first-principles calculation results and these 116 experimental data. The new B3LYP functional is further tested by applying it to calculate the ionization potentials of 24 molecules of the G2 test set. The 6-311+G(3{\it df},2{\it p}) basis set is employed in the calculation, and the resulting root-mean-square error is reduced to 2.2 kcal$\cdot$mol$^{-1}$ in comparison to 3.6 kcal$\cdot$mol$^{-1}$ of conventional B3LYP/6-311+G(3{\it df},2{\it p}) calculation.Comment: 10 pages, 1figur

On the Narrative Features of British Sitcoms: Take The IT Crowd and Yes, Prime Minister as Examples

In recent years, British TV dramas have been a glaring phenomenon and the “new favorite” of fans who love watching overseas TV plays. This paper takes two TV dramas of The IT Crowd and Yes, Prime Minister for case studies, explores the narrative features of British sitcom from dramatic narrative tendency, core narration of “people”, self-deprecating humor, unity of conflict and social significance, concludes three points of inspiration for China’s film and television creation: “learn” instead of “imitate”, “serious” instead of “funny”, “modern” as well as “traditional.”

Binary pulsars as probes of a Galactic dark matter disk

As a binary pulsar moves through a wind of dark matter particles, the resulting dynamical friction modifies the binary's orbit. We study this effect for the double disk dark matter (DDDM) scenario, where a fraction of the dark matter is dissipative and settles into a thin disk. For binaries within the dark disk, this effect is enhanced due to the higher dark matter density and lower velocity dispersion of the dark disk, and due to its co-rotation with the baryonic disk.We estimate the effect and compare it with observations for two different limits in the Knudsen number ($Kn$). First, in the case where DDDM is effectively collisionless within the characteristic scale of the binary ($Kn\gg1$) and ignoring the possible interaction between the pair of dark matter wakes. Second, in the fully collisional case ($Kn\ll1$), where a fluid description can be adopted and the interaction of the pair of wakes is taken into account. We find that the change in the orbital period is of the same order of magnitude in both limits. A comparison with observations reveals good prospects to probe currently allowed DDDM models with timing data from binary pulsars in the near future. We finally comment on the possibility of extending the analysis to the intermediate (rarefied gas) case with $Kn\sim1$.Comment: 15 pages, 6 figures. Few comments and references added, version accepted for publication in Physics of the Dark Universe (PDU

(E)-Ethyl 2-cyano-3-(3,4-dihydr­oxy-5-nitro­phen­yl)acrylate

The title compound, C12H10N2O6, was synthesized via a Knoevenagel condensation and crystallized from ethanol. In the crystal, strong classical inter­molecular O—H⋯O hydrogen bonds and weak C—H⋯N contacts link the mol­ecules into ribbons extending along [010]. Intra­molecular O—H⋯O and C—H⋯N contacts support the planar conformation of the mol­ecules (mean deivation 0.0270 Å)

(2,9-Dimethyl-1,10-phenanthroline-κ2 N,N′)bis­(2-hydroxy­benzoato)-κO;κ2 O,O′-cobalt(II)

In the title compound, [Co(C7H5O3)2(C14H12N2)], the CoII ion is five-coordinated by two N atoms from one 2,9-dimethyl-1,10-phenanthroline (dmphen) ligand and three O atoms from two 2-hydroxy­benzoate anions in a distorted trigonal bipyramidal geometry. The carboxyl­ate group of one of the two 2-hydroxy­benzoate anions is monodentate with a normal Co—O distance [1.9804 (18) Å], while the other is bidentate with two longer Co—O bonds [2.1981 (18) and 2.1359 (19) Å]. The crystal structure is stabilized by aromatic π–π stacking inter­actions [centroid–centroid distances of 4.0380 (3) and 3.8216 (3) Å between dmphen/dmphen and benzene/dmphen rings, respectively] and C—H⋯π(benzene) inter­actions

In-Sample Policy Iteration for Offline Reinforcement Learning

Offline reinforcement learning (RL) seeks to derive an effective control policy from previously collected data. To circumvent errors due to inadequate data coverage, behavior-regularized methods optimize the control policy while concurrently minimizing deviation from the data collection policy. Nevertheless, these methods often exhibit subpar practical performance, particularly when the offline dataset is collected by sub-optimal policies. In this paper, we propose a novel algorithm employing in-sample policy iteration that substantially enhances behavior-regularized methods in offline RL. The core insight is that by continuously refining the policy used for behavior regularization, in-sample policy iteration gradually improves itself while implicitly avoids querying out-of-sample actions to avert catastrophic learning failures. Our theoretical analysis verifies its ability to learn the in-sample optimal policy, exclusively utilizing actions well-covered by the dataset. Moreover, we propose competitive policy improvement, a technique applying two competitive policies, both of which are trained by iteratively improving over the best competitor. We show that this simple yet potent technique significantly enhances learning efficiency when function approximation is applied. Lastly, experimental results on the D4RL benchmark indicate that our algorithm outperforms previous state-of-the-art methods in most tasks

STAR-RIS Assisted Covert Communications in NOMA Systems

Covert communications assisted by simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) in non-orthogonal multiple access (NOMA) systems have been explored in this paper. In particular, the access point (AP) transmitter adopts NOMA to serve a downlink covert user and a public user. The minimum detection error probability (DEP) at the warden is derived considering the uncertainty of its background noise, which is used as a covertness constraint. We aim at maximizing the covert rate of the system by jointly optimizing APs transmit power and passive beamforming of STAR-RIS, under the covertness and quality of service (QoS) constraints. An iterative algorithm is proposed to effectively solve the non-convex optimization problem. Simulation results show that the proposed scheme significantly outperforms the conventional RIS-based scheme in ensuring system covert performance.Comment: arXiv admin note: text overlap with arXiv:2305.04930, arXiv:2305.0399

Low-complexity Resource Allocation for User Paired RSMA in Future 6G Wireless Networks

Rate-splitting multiple access (RSMA) uplink requires optimization of decoding order and power allocation, while decoding order is a discrete variable, and it is very complex to find the optimal decoding order if the number of users is large enough. This letter proposes a low-complexity user pairing-based resource allocation algorithm with the objective of minimizing the maximum latency, which significantly reduces the computational complexity and also achieves similar performance to unpaired uplink RSMA. A closed-form expression for power and bandwidth allocation is first derived, and then a bisection method is used to determine the optimal resource allocation. Finally, the proposed algorithm is compared with unpaired RSMA, paired NOMA and unpaired NOMA. The results demonstrate the effectiveness of the proposed algorithm

2-(2-Hydroxy­ethyl­amino)-3-phenyl-1-benzofuro[3,2-d]pyrimidin-4(3H)-one dichloro­methane hemisolvate

In the title compound, C18H15N3O3·0.5CH2Cl2, the fused ring benzofuro[2,3-d]pyrimidine system is essentially planar [maximum deviation 0.029 (1) Å]. The planes of the pyrimidinone and phenyl rings are nearly perpendicular [dihedral angle = 87.50 (14)°]. The packing of the mol­ecules in the crystal structure is governed mainly by inter­molecular O—H⋯O and N—H⋯O hydrogen-bonding inter­actions and inter­molecular π–π inter­actions between benzofuro[3,2-d]pyrimidine units [the interplanar distances are ca 3.4 and 3.5 Å, and the distances between adjacent ring centroids are in the range 3.64 (1)–3.76 (1) Å]. The dichloromethane solvent molecule lies on a special position