A quasi-static approximation (QSA) for modified gravity can be applied in a number of ways. We consider three different analytical formulations based on applying this to: (1) the field equations; (2) equations two metric potentials; (3) use attractor solution derived within Equation State (EoS) approach. assess veracity these implementations effective gravitational constant ($\mu$) and slip par...

In the static field limit, the vibrational hyperpolarizability consists of two contributions due to: ~1! the shift in the equilibrium geometry ~known as nuclear relaxation!, and ~2! the change in the shape of the potential energy surface ~known as curvature!. Simple finite field methods have previously been developed for evaluating these static field contributions and also for determining the e...