<p>The paper examines synergistic effects of temperature and mechanical external forces on the potential energy surfaces. After formalizing the quantitative introduction of temperature in the potential energy surface, the analysis is given to its effect on the potential energy surface. If the temperature is considered solely, the phase transition structure emerges in the potential energy surface, but the minima in the potential energy surface are equivalent. However, if the synergistic effect of temperature and mechanical force is considered, the results are dramatic, since the phase transition pattern emerges, but the minima in the potential energy surface are no longer equivalent. This study may indicate possible simulations that will shed light on the Epstein effect of post-vibrational interactions.</p>