The approximation of experimental data in gases:

q_gas = Z (376 x + x ⁶)/(1428 -1206 x ^1/2 + 690 x + x ⁶) ,

where x= { Z _t ^{(0.03 -0.017 ξ)} ξ } ^{1 +0.4/Z} , ξ = V/V ₀ Z ^-0.52.

The approximation of experimental data in solid:

q_solid = Z (12 y + y ⁴)/(0.07/y + 6 + 0.3 y ^1/2 + 10.37 y + y ⁴) ,

where y= { Z _t ^{(-0.019 ξ)} ξ/1.68 } ^{1 +1.8/Z} , ξ = V/V ₀ Z ^-0.52.