A practical method for phase equilibrium calculations using the equation of state for a perfect solid and a perfect liquid is shown along with examples of Excel worksheets. The molecular systems of a perfect solid and a perfect liquid are assumed to be composed of single-type spherical molecules. The molecular interaction is expressed by a Lennard-Jones potential function. The pressure and internal energy of the system are expressed as functions of temperature and volume. Other thermodynamic functions such as entropy are also given as functions of temperature and volume. A thermodynamic constancy test is performed.完全固体・完全液体の状態方程式 v3に基づいて、相転移を計算する方法を示した。エクセルのワークシートを使って、ギブズエネルギーやその他の熱力学量を温度と体積の関数として得ることができる。VBAプログラムの例も添付した。熱力学的な恒等式を用いて、数値計算に大きな矛盾がないことを確かめた
