Dark Energy and the mass of galaxy clusters

Up to now, Dark Energy evidences are based on the dynamics of the universe on very large scales, above 1 Gpc. Assuming it continues to behave like a cosmological constant $\mathrm{\Lambda }$ on much smaller scales, I discuss its effects on the motion of non-relativistic test-particles in a weak gravitational field and I propose a way to detect evidences of $\mathrm{\Lambda }\mathrm{\ne }0$ at the scale of about 1 Mpc: the main ingredient is the measurement of galaxy cluster masses.