Electronic energy functionals: Levy–Lieb principle within the ground state path integral quantum Monte Carlo

We propose a theoretical/computational protocol based on the use of the Ground State Path Integral Quantum Monte Carlo for the calculation of the kinetic and Coulomb energy density for a system of N interacting electrons in an external potential. The idea is based on the derivation of the energy densities via the (N ? 1)‐conditional probability density within the framework of the Levy–Lieb constrained search principle. The consequences for the development of energy functionals within the context of density functional theory are discussed. We propose also the possibility of going beyond the energy densities and extend this idea to a computational procedure where the (N ? 1)‐conditional probability is an implicit functional of the electron density, independently from the external potential. In principle, such a procedure paves the way for an on‐the‐fly determination of the energy functional for any system. © 2012 Wiley Periodicals, Inc.     

氨工质焓与熵的新关联式

本文根据统计力学与热力学剩余函数理论,结合本课题组已建立的氨工质新状态方程,推导出一则可供精确确定氨的焓（ｈ）与熵（ｓ）参数的新关联式。新关联式形式简单．可靠,精度很高,具有显著的理论与应用价值。     

Atomically Tailored Gold Nanoclusters for Catalytic Application

Recent advances in the synthetic chemistry of atomically precise metal nanoclusters (NCs) have significantly broadened the accessible sizes and structures. Such particles are well defined and have intriguing properties, thus, they are attractive for catalysis. Especially, those NCs with identical size but different core (or surface) structure provide unique opportunities that allow the specific role of the core and the surface to be mapped out without complication by the size effect. Herein, we summarize recent work with isomeric Au_n NCs protected by ligands and isostructural NCs but with different surface ligands. The highlighted work includes catalysis by spherical and rod‐shaped Au₂₅ (with different ligands), quasi‐isomeric Au₂₈(SR)₂₀ with different R groups, structural isomers of Au₃₈(SR)₂₄ (with identical R) and Au₃₈S₂(SR)₂₀ with body‐centred cubic (bcc) structure, and isostructural [Au₃₈L₂₀(PPh₃)₄]²⁺ (different L). These isomeric and/or isostructural NCs have provided valuable insights into the respective roles of the kernel, surface staples, and the type of ligands on catalysis. Future studies will lead to fundamental advances and development of tailor‐made catalysts.     

Generation of Accelerating Beams along Arbitrary Trajectories

A phase superposition approach for generating arbitrarily accelerating beams is proposed, where the superimposed phase is composed of multiple sub‐phases, each of which determines an independent sub‐beam or sub‐trajectory. Further, an effective algorithm is developed to improve the uniformity of the intensity along the arbitrary trajectory by introducing phase‐shift factors. Experimental results are consistent with numerical simulations. The proposed method can be extended to nonparaxial fields, and it also breaks the previous trajectory restrictions. The arbitrarily accelerating optical beams can pave the way for optically moving particles along a predefined trajectory. The property of such beams following arbitrary trajectories is likely to give rise to new applications in wave front control, flexible optical manipulation, and optical transport and guidance of particles.     

Analytical applications of neotridecanohydroxamin acid as stationary phase in extraction chromatography

Some analytical applications of neotridecanohxdroxamic acid used as stationary phase in extraction chromatography columns are reported. Separations of Am-U-Th and Np-Pu are obtained in aqueous solutions and under different experimental conditions. The hydroxamic acid shows a peculiar selectivity for Np(IV) and Pu(IV) at pH=0, and the two elements can be separated according to their respective valencies. A selective method for the determination of²³⁷Np and²³⁹Pu in urine is also described. The final recoveries are 73.5% for plutonium and 82.3% for neptunium, the decontamination factors and the sensitivity limits are suitable for the radiotoxicological detection of both elements.     

A Note on the Initial Condition of the Differential Equation Which Defines Proper Quantum Topological Subspaces

We analyze Baders variational procedure (BVP) to define Proper Quantum Topological Subspaces (PQTS) in multiatomic systems (MAS). In particular, we explicitly treat the problem of the initial condition of the partial differential equation resulting from BVP and defining the boundary of PQTS. We show that in general for MAS where nuclei correspond to spherical regions of constant (uniform) distribution the proper initial condition associated with the equation defining single atoms automatically emerges from the fundamental physical and mathematical hypothesis on which BVP is based. Our results justify the uniqueness of Baders partition of atoms in molecules on the basis of an a priori mathematical argument implicitly contained in the theory rather than on an a posteriori chemical one as done so far.     

On the existence of a third-order phase transition beyond the Andrews critical point: a molecular dynamics study

The possibility of the existence of a gas-liquid third order phase transition for fluids is becoming a subject of growing interest. Experimental work suggests its existence for specific systems while recent theoretical models claim its universality. In this work, we employ Molecular Dynamics and investigate the third-order phase transition beyond the Andrews critical point by treating a system of Lennard-Jones particles along three isotherms. Two partial derivatives of the Gibbs free energy are measured, namely the molar constant pressure heat capacity and isothermal compressibility. The convergence of these simulations with respect to the system size as well as the cut-off radius is carefully checked. The obtained results show that partial derivatives certainly do not present sharp cusp singularities at the maxima, and actually suggest that there are no singularities at all. On these basis we then conclude that a third-order phase transition in the considered temperature region: T? ≥ 1.36 may indeed not exist.