Elastic Anomalies of Crystalline 4He at T=0

Elastic constants for hcp4He are investigated at zero temperature, from close to the melting pressure up to 14 MPa approximately. Well known relations of these quantities are used to analyze the results. A reliable model wave function is used in the calculations. We show that the linear compressibility has a non-isotropic character in a range of densities rather than the expected isotropic behavior. A fact that suggests that the relation among elastic constants that depends on a constant value of the structure parameters ratio c/a for hcp quantum crystals should not be used to extract an elastic constant from experimental data.