Romero-Rochín Víctor
Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 México, DF Mexico.
J Phys Chem B. 2005 Nov 17;109(45):21364-8. doi: 10.1021/jp0443052.
We study a fluid of interacting atoms confined by a three-dimensional anisotropic harmonic potential, similar to those produced by the magnetic traps used to confine cold atoms. We show that instead of the usual thermodynamic variables pressure and volume, no longer existing in this case, there appear "new" variables: the volume is replaced by (the inverse cube of) the geometric average of the oscillator frequencies of the trap, and the hydrostatic pressure is replaced by an intensive variable, conjugate to the previous one, and responsible for the mechanical equilibrium of the fluid in the trap. We discuss the origin and physical meaning of these new variables. With the aid of molecular dynamics simulations we show the emergence of novel liquid, vapor and solid-like phases in a classical fluid. In particular, we calculate the liquid-vapor-like coexistence curve and show evidence for the appearance of a critical point. These phase transitions should be observable in fluids of not-so-cold alkaline atoms.
我们研究了一种由三维各向异性谐振子势约束的相互作用原子流体，这与用于约束冷原子的磁阱所产生的势类似。我们发现，在此情形下，通常的热力学变量压力和体积不再存在，而是出现了“新”变量：体积被阱的振荡频率的几何平均值（的立方倒数）所取代，静水压则被一个强度变量所取代，该强度变量与前一个变量共轭，并负责流体在阱中的力学平衡。我们讨论了这些新变量的起源和物理意义。借助分子动力学模拟，我们展示了经典流体中新型液体、蒸汽和类固相的出现。特别是，我们计算了类液 - 气共存曲线，并给出了临界点出现的证据。这些相变在不太冷的碱金属原子流体中应该是可观测的。
