División de Ciencias e Ingenierías, Campus León, Universidad de Guanajuato, Loma del Bosque 103, Lomas del Campestre, 37150 León, Guanajuato, Mexico.
J Chem Phys. 2013 Nov 14;139(18):184505. doi: 10.1063/1.4829769.
The liquid-vapor coexistence (LV) of bulk and confined quantum fluids has been studied by Monte Carlo computer simulation for particles interacting via a semiclassical effective pair potential Veff(r) = VLJ + VQ, where VLJ is the Lennard-Jones 12-6 potential (LJ) and VQ is the first-order Wigner-Kirkwood (WK-1) quantum potential, that depends on β = 1∕kT and de Boer's quantumness parameter Λ=h/σ√mε, where k and h are the Boltzmann's and Planck's constants, respectively, m is the particle's mass, T is the temperature of the system, and σ and ε are the LJ potential parameters. The non-conformal properties of the system of particles interacting via the effective pair potential Veff(r) are due to Λ, since the LV phase diagram is modified by varying Λ. We found that the WK-1 system gives an accurate description of the LV coexistence for bulk phases of several quantum fluids, obtained by the Gibbs Ensemble Monte Carlo method (GEMC). Confinement effects were introduced using the Canonical Ensemble (NVT) to simulate quantum fluids contained within parallel hard walls separated by a distance Lp, within the range 2σ ≤ Lp ≤ 6σ. The critical temperature of the system is reduced by decreasing Lp and increasing Λ, and the liquid-vapor transition is not longer observed for Lp∕σ < 2, in contrast to what has been observed for the classical system.
大块和受限量子流体的液-气相共存（LV）已通过蒙特卡罗计算机模拟研究，模拟的粒子通过半经典有效对势 Veff(r)相互作用，其中Veff(r) = VLJ + VQ，VLJ 是 Lennard-Jones 12-6 势（LJ），VQ 是一阶 Wigner-Kirkwood（WK-1）量子势，它取决于β=1∕kT 和 de Boer 的量子参数 Λ=h/σ√mε，其中 k 和 h 分别是玻尔兹曼和普朗克常数，m 是粒子的质量，T 是系统的温度，σ和ε是 LJ 势参数。由于 Λ，通过有效对势 Veff(r)相互作用的粒子系统具有非共形性质，因为 LV 相图通过改变 Λ 而改变。我们发现，WK-1 系统通过吉布斯系综蒙特卡罗方法（GEMC）获得的几种量子流体的大块相的 LV 共存提供了准确的描述。使用正则系综（NVT）引入限制效应，以模拟由距离 Lp 隔开的平行硬壁所包含的量子流体，其中 2σ ≤ Lp ≤ 6σ。通过减小 Lp 和增加 Λ 来降低系统的临界温度，并且对于 Lp∕σ < 2，不再观察到液-气相转变，与经典系统的观察结果相反。
