Theory of Quantum-Mechanical Effects at the Liquid-Gas Critical Point

A theory is developed, with use of Feynman's effective-potential method, for the quantum-mechanical (QM) effects on the critical properties of Lennard-Jones fluids. The theory (i) provides a good description of the QM effects on the critical temperature, pressure, and volume; (ii) predicts no QM effects on critical exponents; (iii) correctly describes the QM corrections to critical amplitudes; and (iv) introduces QM corrections to the "correction-to-scaling" confluent singular terms obtained via classical renormalization-group theory.