Fitting complex potential energy surfaces to simple model potentials: application of the simplex-annealing method

A stochastic method of optimization, which combines simulated annealing with simplex, is implemented to fit the parameters of a simple model potential. The main characteristic of the method is that it explores the whole space of the parameters of the model potential, and therefore it is very efficient in locating the global minimum of the cost function, in addition to being independent of the initial guess of the parameters. The method is employed to fit the complex intermolecular potential energy surface of the dimer of water, using as a reference the spectroscopic quality anisotropic site-site potential of Feller et al. The simple model potential chosen for its reparameterization is the MCY model potential of Clementi et al. The quality of the fit is assessed by comparing the geometry of the minimum, the harmonic frequencies, and the second virial coefficients of the parameterized potential with the reference one. Finally, to prove more rigorously the robustness of this method, it is compared with standard nonstochastic methods of optimization.     

Über Reaktionen von Nitrosophenolen, 4. Mitt.: Reaktion von Nitrosonaphtholen mit Naphtholen

Zusammenfassung Die Reaktion von 1-Nitroso-2-naphthol mit 1-und 2-Naphthol sowie die Reaktion von 2-Nitroso-1-naphthol mit 2-Naphthol in Äthanol und in Äther bei Anwesenheit von HNO<sub>3</sub> gibt 5<i>H</i>-Dibenzo[<i>a,j</i>]phenoxazon-(5) (I), 5<i>H</i>-Dibenzo[<i>a,j</i>]phenoxazon-(5)-14-oxid (II), 5<i>H</i>-Dibenzo[<i>a,h</i>]phenoxazon-(5) (III) sowie 5<i>H</i>-Dibenzo[<i>a,h</i>]phenoxazon-(5)-14-oxid (IV). Es wurde ein Reaktionsmechanismus vorgeschlagen und die Konstitution der hergestellten Verbindungen spektrophotometrisch und potentiometrisch bestimmt.<hr><blockquote>The reaction of 1-nitroso-2-naphthol with 2-and 2-naphthol and the reaction of 2-nitroso-1-naphthol with 2-naphthol in ethanol or ether in the presence of nitric acid have been studied. The main reaction products isolated were the dibenzophenoxazones I–IV. The reaction mechanism for their formation is proposed.</blockquote><hr><hr><p></p>Mit 4 Abbildungen     

The Binary System BaF2/AlF3

The system BaF<sub>2</sub>/AlF<sub>3</sub> is investigated by X-ray and D.T.A., and the liquid-solid phase diagram is established. Five ternary fluorides are disclosed: trimorphic BaAlF<sub>5</sub>, Ba<sub>3</sub>Al<sub>2</sub>F<sub>12</sub>, Ba<sub>5</sub>AlF<sub>19</sub>, polymorphic Ba<sub>3</sub>AlF<sub>9</sub> and Ba<sub>5</sub>AlF<sub>13</sub>. Neutron thermodiffractometry experiments are performed to specify some parts of the diagram. The cell parameters of the fluorides are given and the results are discussed and compared with those of the previous works.     

Crystal and molecular structure of [9-(2′-tosylaminophenyl)-6-methylthio-3-acetyl-5,7,8-triazanone-3,6,8-thien-2-one]

Institute for Applied Physics, Academy of Sciences of the Moldavian SSR. Institute of Chemistry, Academy of Sciences of the Moldavian SSR. Nat. Research Institute for Physics and Organic Chemistry, Rostov State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 2, pp. 199–202, 1990.     

Regioselectivity of Birch reductive alkylation of biaryls

[reaction: see text] The regioselectivity of the Birch reductive alkylation of polysubstituted biaryls has been investigated. Results indicate that regioselectivity is affected by the electronic nature of substituents on both aromatic rings. The electron-rich 3,5-dimethoxyphenyl moiety is selectively reduced and then alkylated, while phenols and aniline are not dearomatized under these conditions. Biaryls possessing a phenol moiety are alkylated on the second ring, providing that the acidic proton has been removed prior to the Li/NH3 reduction.     

Synthesis of 2′,3′-dihydrosolanesyl analogues of β-d-arabinofuranosyl-1-monophosphoryldecaprenol with promising antimycobacterial activity

Two new hydrolytically stable analogues of β-d-arabinofuranosyl-1-monophosphoryldecaprenol, the donor substrate for mycobacterial arabinosyltransferase, have been prepared. Biological evaluation of these compounds in vitro against <em>Mycobacterium tuberculosis</em> H<sub>37</sub>Rv strain revealed a promising activity.     

Examining the balance between efficiency and resilience in closed-loop supply chains

Central European Journal of Operations Research - We study a hybrid system where the demand of customers can be satisfied by both manufacturing new products and remanufacturing used products. To...     

Triangulations and moduli spaces of Riemann surfaces with group actions

Summary We study that subset of the moduli space <img src="/content/802746300253420r/229_2007_Article_BF02567818_TeX2GIFIE1.gif" alt=" $$\bar M^g $$ " align="middle" border="0"> of stable genus<i>g</i>,<i>g</i>>1, Riemann surfaces which consists of such stable Riemann surfaces on which a given finite group<i>F</i> acts. We show first that this subset is compact. It turns out that, for general finite groups<i>F</i>, the above subset is not connected. We show, however, that for ℤ<sub>2</sub> actions this subset<i>is</i> connected. Finally, we show that even in the moduli space of<i>smooth</i> genus<i>g</i> Riemann surfaces, the subset of those Riemann surfaces on which ℤ<sub>2</sub> acts<i>is</i> connected. In view of deliberations of Klein ([8]), this was somewhat surprising. These results are based on new coordinates for moduli spaces. These coordinates are obtained by certain<i>regular</i> triangulations of Riemann surfaces. These triangulations play an important role also elsewhere, for instance in approximating eigenfunctions of the Laplace operator numerically. This work has been supported by the European Communities Science Plan Project No SCI<sup>*</sup>-CT91 (TSTS) “Computational Methods in the Theory of Riemann Surfaces and Algebraic Curves,” by Academy of Finland and by the Swiss National Science Foundation Grant 20-34099.92. We thank M. C. Petrus for providing excellent motivation for this work. This article was processed by the author using the LATEX style file<i>cljourl</i> from Springer-Verlag.     

Kneser-type oscillation criteria for self-adjoint two-term differential equations

It is proved that the even-order equation<i>y</i> <sup> <i>(2n)</i> </sup> <i>+p(t)y</i>=0 is (<i>n,n</i>) oscillatory at <img src="/content/P27410776Q7322T3/xxlarge8734.gif" alt="infin" align="MIDDLE" border="0"> if<table width="100%"><tbody><tr><td align="left"> <img src="/content/P27410776Q7322T3/11290_2005_Article_BF02261699_TeX2GIFE1.gif" alt=" $$\mathop {\lim }\limits_{t \to \infty } ( - 1)^n \log t\int_t^\infty {s^{2n - 1} } \left( {p(s) + \frac{{\mu _{2n} }}{{s^{2n} }}} \right) ds< - K_n $$ " align="middle" vspace="20%" border="0">