Very high density liquid

Where mobility data are available over a considerable range of temperature, the activation energy is often found to be temperature-dependent. Thus, in n-pentane the activation energy increases with temperature whereas in ethane it decreases (Schmidt, 1977). Undoubtedly, part of the explanation lies in the temperature dependence of density, but detailed understanding is lacking. In very high mobility liquids, the mobility is expected to decrease with temperature as in the case of the quasi-free mobility. Here again, as pointed out by Munoz (1991), density is the main determinant, and similar results can be expected at the same density by different combinations of temperature and pressure. This is true for LAr, TMS, and NP, but methane seems to be an exception. 

The transition to the continuum fluid may be mimicked by a discretization of the model choosing > 1. To this end, Panagiotopoulos and Kumar [292] performed simulations for several integer ratios 1 < < 5. For — 2 the tricritical point is shifted to very high density and was not exactly located. The absence of a liquid-vapor transition for = 1 and 2 appears to follow from solidification, before a liquid is formed. For > 3, ordinary liquid-vapor critical points were observed which were consistent with Ising-like behavior. Obviously, for finely discretisized lattice models the behavior approaches that of the continuum RPM. Already at = 4 the critical parameters of the lattice and continuum RPM agree closely. From the computational point of view, the exploitation of these discretization effects may open many possibilities for methodological improvements of simulations [292], From the fundamental point of view these discretization effects need to be explored in detail. 

Nearly all barometers and most manometers use mercury as the working fluid, despite the fact that it is a toxic substance with a harmful vapor. The reason is that mercury has a very high density (13.6 g/mL) compared with most other liquids. Since the height of the liquid in a column is inversely proportional to the liquid s density, this property allows the construction of manageably small barometers and manometers. 

As shown in the previous section, the inertial confinement scheme involves creation of very high densities for very short times. A small piece of soUd or liquid material (a fuel pellet) is compressed by intense beams of energy (called driver) to the desired densities, and the confinement is simply achieved by the finite free expansion time of the compressed pellet. 

A recent development has been the suggested existence of a very high-density (VHDA) polyamorph of a—H2O first indicated from analysis of neutron scattering data [63,87,88,98-101], That observation would then imply the existence of a series of LLPT or polyamorphic events occurring in H2O and perhaps other systems as a function of p-T conditions. These could then culminate in the liquid-gas transition observed at the lowest density (Fig. Ic) [5], However, the observed VHDA polyamorph of a—H2O might also be related to HDA via a continuous series of structural relaxation events, although extensive series of recent experiments... 

The possibility of the existence of a second liquid-liquid phase transition in water was discussed following the discovery [42] of an even higher density amorphous state, named very high density amorphous (VHDA). However, unlike the LDA-HDA transition, this has since been widely accepted to be a continuous change in the structure [74]. 

The stronger enhancement at low densities could be attributed phenomenologically to an increase in the Stoner parameter a. This approach leads to an incorrect description of the physics as may be seen by the following argument (Warren, 1984 Chapman and March, 1988). The plot in Fig. 3.2 shows that the enhancement of the measured susceptibility is limited near the Curie values calculated for cesium on the coexistence curve. Between the peak and the critical point, the liquid-state susceptibility tends to follow the Curie law (x oc p/T). Stoner enhancement, however, can increase without limit and the susceptibility actually diverges at the transition point of a metallic ferromagnet. In contrast. Curie law behavior is the limit expected from Eq. (3.3) if the enhancement is due to a very high density of states. 

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