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We present how to treat the polarization effect on the static and dynamic properties in molten lithium iodide (LiI). Iodide anion has the biggest polarizability among all the halogen anions and lithium cation has the smallest polarizability among all the alkaline metal cations. The mass ratio of I to Li is 18.3 and the ion size ratio is 3.6, so we expect the most drastic characteristic motion of ions is observed. The softness of the iodide ion was examined by modifying the repulsive term in the Born-Mayer-Huggins type potential function in the previous work. In the present work we consider the polarizability of iodide ion with the dipole rod method in which the dipole rod is put at the center of mass and we solve the Euler-Lagrange equation. This method is one type of Car-Parrinello method.

The liquid-glass transition in molten lithium iodide has been investigated by means of constant-pressure and constant-temperature molecular dynamics. Both static and dynamic properties were calculated, with a microscopic analysis of the ionic motions. In the vicinity of the glass transition, the mean-square displacement shows a non-linear time dependence and the incoherent scattering function is well fitted by a ‘stretched exponential’ function. The maximum value of the non-Gaussian parameter increases drastically on approaching the glass transition. The glass transition temperature is estimated by trapping diffusion theory.

Molecular dynamics simulation for a 1:5 molar mixture of lithium bromide and lithium iodide was carried out with Born-Mayer-Huggins type pair potential. The self-exchange velocity of the iodide ion is greater than that of the bromide ion although the iodide ion is heavier than the bromide ion. This “anion Chemla effect” is explained from the difference in the barrier height of the potential function which the bromide ion or the iodide ion feels from the lithium ion. The pair distribution functions, the angular correlation functions and the velocity autocorrelation functions are also examined.

As a part of the development of organic fluorescent reagents, bimane derivatives were coupled to guanosine 3'-monophosphate, and they were shown to be useful fluorogenic substrates for the assay of ribonuclease T1.

The liquid‐glass transition of LiI has been investigated by means of the constant‐temperature and constant‐pressure molecular dynamics method. Because LiI is one of the most simple examples of the coulombic system and the most contrasted combination of the cation and anion among all alkaline halides (the mass ratio of I to Li is 18.3 and the ionic size ratio is 3.6), we have expected to see the ionic motion most drastically. We calculated both static and dynamic properties with microscopic analyses for ionic motions. In the vicinity of the glass transition, the mean‐square displacement shows a non‐t‐linear behavior, sometimes called a subdiffusive behavior, and the incoherent scattering function are well fitted by ‘‘stretched exponential’’ function. The non‐Gaussian parameter as a function of time has a large maximum, and the product of the maximum value and the corresponding time increases sharply as approaching the glass transition. All these anomalous characteristic behaviors, as well as those found for the binary soft‐sphere system, are in good agreement with the prediction of the trapping diffusion theory. We discuss the validity of this theory.

Molecular dynamics simulation of molten LiBr was performed at 1000 K and 1500 K with the Born-Mayer-Huggins type potential functions. The temperature effects on the g ( r ) functions, the coordination numbers, the angular distribution functions, the diffusion coefficients, the velocity autocorrelation functions, and the power spectra are examined.

The liquid structure of dimethyl sulfoxide (DMSO) was investigated by X-ray diffraction. The intramolecular structure parameters were obtained as follows: S = 0 150(1) pm, C - S 180(1) pm, nonbonding C · · · O 267(4) pm and C · · · C 271 (7) pm. It is suggested that the molecular arrangement in the liquid state is similar to that in the solid state. It is pointed out that not only the value but also the position of the dipole mom ent vector in the molecule is essential for dipoledipole intermolecular interactions and that the latter factor results in a higher melting point of DMSO than of N ,N -dimethylformamide in spite of their similar dipole moments.

The structure of N,N-dimethylformamide (DMF) was determined at 25 °C by means of X-ray diffraction using a θ-θ type X-ray diffractometer. The least-squares analysis of the reduced intensities results that a DMF molecule has a practically planar skeletal structure in the liquid state. Intramolecular structural parameters within a DMF molecule were determined as follows: C=O; 1.24 A, N–C(CHO); 1.35 A, and N–C(CH3); 1.45 A. The bond lengths are not appreciably different from those found in the gas phase, except for the C=O length, which is slightly longer by 0.04 A in the liquid state than in the gaseous one. The radial distribution curve of DMF shows that the intermolecular arrangement of DMF molecules is practically fully disordered and no evidence has been found for the cluster formation of DMF molecules in the liquid state. The experimental result for the weak intermolecular interactions between DMF molecules is supported by ab initio MO-SCF calculations.

The liquid structure of N-methylformamide (NMF) has been investigated by the X-ray diffraction method and the ab initio MO-SCF method. The structure parameters within a molecule were obtained as follows: C=O : 122(1) pm, C(methyl)–N : 145(2) pm, C(carbonyl)–N : 134(2) pm, N···O : 222(4) pm, C(methyl)···O : 278(6) pm. The intermolecular hydrogen–bonded N···O distance was estimated to be 298(11) pm. A linear and flexible chain structure was proposed for the liquid structure of NMF on the basis of scattered intensity data by the X-ray diffraction method and of interaction energies and geometries of hydrogen-bonded NMF molecules calculated by the ab initio MO calculations.

Liquid structures of pure N,N-dimethylformamide (DMF) and acetonitrile (AN) as well as of their 1 : 1 molar mixture were investigated by X-ray diffraction at 25 °C. The careful reinvestigation of pure DMF led to a good reproducibility of the previous result. Slight deviations in the structural parameters are discussed and a detailed parameter table is reported. A simple model in which each AN molecule has 2 neighbors at an average distance of 330 pm describes the more ordered first neighbor structure of pure AN. The main interaction forming the structure is of dipole–dipole type, in agreement with previous findings. In the 1 : 1 molar mixture a dipole–dipole model also leads to a satisfactory description of the first neighbor structure. The preferred orientation is that with dipoles in the antiparallel position. A central DMF molecule has 1.75 neighboring AN molecules in average at a distance of 316 pm. The same stands for DMF around AN. No evidence for other kinds of interaction, e.g., weak H-bond type i...

The structure of liquid formamide is discussed on the basis of X-ray diffraction measurements and MO calculations. It is concluded that liquid formamide has both chain-like and ring-dimer moieties and that the former ones have a longer life time.