论文标题
平均场模型中的相线，外力不均匀
Phase lines in mean-field models with nonuniform external forces
论文作者
论文摘要
我们查看外部磁场对顺序参数的通用自由能函数描述的系统的影响。外力可能具有任意的空间依赖性，并且顺序参数耦合可能是非线性的。该处理概括了看似不同的作品，例如纯液，液体和聚合物混合物，脂质单层和重力中的电场，流体和nematics中的胶体悬浮液，超级过渡性的溶液，以及激光辐射中的液体混合物。相线和热力学行为是在平均场水平上计算的。我们发现一个``表面''临界点可以比批量临界点更高或更低的温度转移。在这一点之下，从``气体''阶段到``液体''相的过渡是一阶，而在其上方，过渡是二阶的。二阶线受力的空间依赖性影响，而一阶线是通用的。此外，易感性可能会在有限位置$ {\ bf r} $方向发散。在限制中给出了几种分析表达式，其中自由能的扩展是有效的。
We look at the influence of external fields on systems described by generic free energy functional of the order parameter. The external force may have arbitrary spatial dependence, and the order parameter coupling may be nonlinear. The treatment generalizes seemingly disparate works, such as pure fluids, liquid and polymer mixtures, lipid monolayers, and colloidal suspensions in electric fields, fluids and nematics in gravity, solutions in an ultracentrifuge, and liquid mixtures in laser radiation. The phase lines and thermodynamic behavior are calculated at the mean-field level. We find a ``surface'' critical point that can be shifted to higher or lower temperatures than the bulk critical point. Below this point, the transition from a ``gas'' phase to a ``liquid'' phase is first-order, while above it, the transition is second-order. The second-order line is affected by the spatial dependence of the force, while the first-order line is universal. Moreover, the susceptibility may diverge at a finite location ${\bf r}$. Several analytical expressions are given in the limit where a Landau expansion of the free energy is valid.
