Based on the nonlinear dependence of the first coordination number versus of the structure-packing factor (kp), a method for calculating of the Debye temperature for the amorphous structure of a monoatomic substance is proposed. By means of the parameters of pairwise Mie-Lennard-Jones potential, the Debye temperatures were calculated for the crystalline and amorphous structures of a number of pure metals, diamond, Si, Ge. Good agreement is obtained with the estimates of other authors. It is shown that at kp = 0.45556 the minimum of the Helmholtz specific free energy is reached, i.e. this packing is the thermodynamically stable amorphous structure. This work was supported by the Russian Foundation for Basic Research (project no. 18-29-11013_mk) and the program no. I.13 of the Presidium of the Russian Academy of Sciences.