On the role of the quantum fluctuations in a model of an anharmonic crystal

classical and quantum fluctuations depending on the below the low quantum critical dimension. the long-range interaction exponent σ and the spatial dimension d is studied below the lower quantum critical dimension. The equation for the inverse susceptibility is analyzed in the low-temperature regime (λ=0. It is arbitrary) and in the regime of a small quantum parameter (T is arbitrary) excluding the range around T = = 0. It is shown that in the absence of a phase transition in the system, the quantum fluctuations have a stronger impact on the susceptibility of the classical system, in comparison to the impact of the classical (or thermodynamic) fluctuations on the pure quantum system.