The dielectric properties of confined water is of fundamental interest and is still controversial. For water confined in channels with height smaller than h = 8 Å, we found a commensurability effect and an extraordinary decrease in the out-of-plane dielectric constant down to the limit of the dielectric constant of optical water. Spatial resolved polarization density data obtained from molecular dynamics simulations are found to be antisymmetric across the channel and are used as input in a mean-field model for the dielectric constant as a function of the height of the channel for h > 15 Å. Our results are in excellent agreement with a recent experiment [L. Fumagalli

Dielectric properties of nano-confined water are important in several areas of science, i.e. it is relevant in dielectric double layer that exist in practically all heterogeneous fluid-based system. Molecular dynamics simulations are used to predict the in-plane dielectric properties of confined water in planar channels of width ranging from sub-nanometer to bulk. Because of suppressed rotational degrees of freedom near the confining walls the dipole of the water molecules tend to be aligned parallel to the walls which results in a strongly enhanced in-plane dielectric constant (ε || ) reaching values of about 120 for channels with height 8Å< h <10 Å. With increasing width of the channel, we predict that ε || decreases nonlinearly and reaches the bulk value for h > 70Å. A stratified continuum model is proposed that reproduces the h > 10Å dependence of ε || . For sub-nanometer height channels an abnormal behaviour of ε || is found with two orders of magnitude reduction of ε || around h ∼7.5 Å which is attributed to the formation of a particular ice phase which exhibits long-time (∼ µs) stable ferroelectricity. This is of particular importance for the understanding of the influence of confined water on the functioning of biological systems.

The melting behaviors of metal clusters are studied in a wide range by molecular dynamics simulations. The calculated results show that there are fluctuations in the heat capacity curves of some metal clusters due to the strong structural competition; For the 13-, 55-and 147-atom clusters, variations of the melting points with atomic number are almost the same; It is found that for different metal clusters the dynamical stabilities of the octahedral structures can be inferred in

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ARTICLES YOU MAY BE INTERESTED INMolecular dynamical simulations of melting behaviors of metal clusters AIP Advances 5, 047129 (2015); https://doi