Combining stochastic density functional theory with deep potential molecular dynamics to study warm dense matter

In traditional finite-temperature Kohn–Sham density functional theory(KSDFT),the partial occupation of a large number of high-energy KS eigenstates restricts the use of first-principles molecular dynamics methods at extremely high temperatures.However,stochastic density functional theory(SDFT)can overcome this limitation.Recently,SDFT and the related mixed stochastic–deterministic density functional theory,based on a plane-wave basis set,have been implemented in the first-principles electronic structure software ABACUS[Q.Liu and M.Chen,Phys.Rev.B 106,125132(2022)].In this study,we combine SDFT with the Born–Oppenheimer molecular dynamics method to investigate systems with temperatures ranging from a few tens of eV to 1000 eV.Importantly,we train machine-learning-based interatomic models using the SDFT data and employ these deep potential models to simulate large-scale systems with long trajectories.Subsequently,we compute and analyze the structural properties,dynamic properties,and transport coefficients of warm dense matter.

Thermal transport by electrons and ions in warm dense aluminum:A combined density functional theory and deep potential study

We propose an efficient scheme that combines density functional theory(DFT)with deep potentials(DPs),to systematically study convergence issues in the computation of the electronic thermal conductivity of warm dense aluminum(2.7 g/cm^(3)and temperatures ranging from 0.5 eV to 5.0 eV)with respect to the number of k-points,the number of atoms,the broadening parameter,the exchange-correlation functionals,and the pseudopotentials.Furthermore,we obtain the ionic thermal conductivity using the Green–Kubo method in conjunction with DP molecular dynamics simulations,and we study size effects on the ionic thermal conductivity.This work demonstrates that the proposed method is efficient in evaluating both electronic and ionic thermal conductivities of materials.

Variable Learning-Memory Behavior fromπ-Conjugated Ligand to Ligand-Containing Cobalt(II)Complex

In the information-explosion era,developing novel algorithms and memristive devices has become a promising concept for next-generation capacity enlargement technology.Organic small molecule-based devices displaying superior learning-memory performance have attracted much attention,except for the existence of poor heat-resilience and mediocre conductivity.In this paper,a strategy of transforming an organic-type data-storage material to metal complex is proposed to resolve these intrinsic issues.A pristine NDI-derivative(NIPy)and its corresponding Co(II)complex(CoNIPy)are synthesized for the purpose of electrical property investigation.CoNIPy complex-based memristive device exhibits superior ternary WORM memory performance compared with the binary behavior of NIPy,including>104 s of reading,lower threshold voltage(V_(th)),1:10^(2):10^(5)of OFF/ON1/ON2 current ratio,and long-term stability in heating environment.The variable learning-memory behavior can be attributed to the enhanced ligand-to-metal charge transfer(LMCT)and improved redox activity after the introduction of central metal atom and coordination bond.These studies on material innovation and optimal performance are of great importance not only for environmentally-robust memristive devices but also for practical application of a host of organic electronic devices.

Signature of the hydrogen-bonded environment of liquid water in X-ray emission spectra from first-principles calculations

Based on ab initio molecular dynamics simulations and density functional theory, we performed a systematic theoretical study to elucidate the correlation between the H-bonded environment and X- ray emission spectra of liquid water. The spectra generated from excited water molecules embedded in an intact H-bonded environment yield broader spectral peaks and a larger spectral range than the spectra generated from water molecules in a broken H-bonded environment. Such differences are caused by the local electronic structures on the excited water molecules within the core-hole lifetime that evolve differently through the rearrangement of neighboring water molecules in different H-bonded environments.