The IR and NMR spectra were coupled with quantum chemical calculations in DFT approach usingthe hybrid B3LYP exchange-correlation functional to confirm the structure of 2-methoxycarbonyl-7-methyl-1,3-thiazino[3,2-b][1,2,4]triazine-4,8-dione 2d.

We extend the exchange fluctuation theorem for energy exchange between thermal quantum systems beyond the assumption of molecular chaos, and describe the nonequilibrium exchange dynamics of correlated quantum states. The relation quantifies how the tendency for systems to equilibrate is modified in high-correlation environments. In addition, a more abstract approach leads us to a "correlation f...

Starting from the general expression for the ground state correlation energy in the adiabatic-connection fluctuation-dissipation theorem (ACFDT) framework, it is shown that the dielectric matrix formulation, which is usually applied to calculate the direct random phase approximation (dRPA) correlation energy, can be used for alternative RPA expressions including exchange effects. Within this fa...

The exchange hole, which is one of the principal constituents of the density functional formalism, can be used to design accurate range-separated hybrid functionals in association with appropriate correlation. In this regard, the exchange hole derived from the density matrix expansion has gained attention due to its fulfillment of some of the desired exact constraints. Thus, the new long-range ...

cation exchange capacity and specific surface area are among some of the important soil characteristics the direct measurement of which is laborious, costly and time consuming. therefore, fractal dimension of particle size distribution has been widely studied in relation with many such dynamic and static processes as transmission of water and solutes, water holding capacity, heat storage and co...

in this study business operations and liquidity and credit risk on price fluctuations on the stock exchange since 2010 to 2013 has been tehran distance. the sample consisted of 76 company the systematic elimination method is selected. the company had a total of 304 years, in this study, the hypothesis of linear regression and correlation to analyse the data and test hypotheses eviews software i...

First-principles derivation is given for the heuristic exchange-hole model of London dispersion forces by Becke and Johnson [J. Chem. Phys. 122, 154104 (2005)]. A one-term approximation is used for the dynamic charge density response function, and it is shown that a central nonempirical ingredient of the approximate nonexpanded dispersion energy is the charge density autocorrelation function, a...

The derivative discontinuity is a key concept in electronic structure theory in general and density functional theory in particular. The electronic energy of a quantum system exhibits derivative discontinuities with respect to different degrees of freedom that are a consequence of the integer nature of electrons. The classical understanding refers to the derivative discontinuity of the total en...

Previous first-principles calculations of the melting properties of Si, based on the local-density approximation ~LDA! for electronic exchange-correlation energy, underpredict the melting temperature by ;20 %. We present new first-principles results indicating that a large part of this problem is due to noncancellation of exchange-correlation errors between the semiconducting solid and the meta...