卡普斯钦斯基方程

这样计算的晶格能较为准确，与准确值在一般情况下相差不到5 %。

此外，在晶格能已知的情况下，能够用这个方程确定离子半径。这对于复杂离子很有用，例如硫酸根 (SO2−4)或磷酸根 (PO3−4)。

The Kapustinskii equation calculates the lattice energy UL for an ionic crystal, which is experimentally difficult to determine. It is named after Anatoli Fedorovich Kapustinskii who published the formula in 1956. （公式略）

The calculated lattice energy gives a good estimation for the Born–Landé equation; the real value differs in most cases by less than 5%.

Furthermore, one is able to determine the ionic radii (or more properly, the thermochemical radius) using the Kapustinskii equation when the lattice energy is known. This is useful for rather complex ions like sulfate (SO2−4) or phosphate (PO3−4).

Derivation from the Born–Landé equation

Kapustinskii originally proposed the following simpler form, which he faulted as "associated with antiquated concepts of the character of repulsion forces". （公式略）

Here, K' = 1.079×10−4 J·m·mol−1. This form of the Kapustinskii equation may be derived as an approximation of the Born–Landé equation, below. （公式略）

Kapustinskii replaced r0, the measured distance between ions, with the sum of the corresponding ionic radii. In addition, the Born exponent, n, was assumed to have a mean value of 9. Finally, Kapustinskii noted that the Madelung constant, M, was approximately 0.88 times the number of ions in the empirical formula. The derivation of the later form of the Kapustinskii equation followed similar logic, starting from the quantum chemical treatment in which the final term is 1 − ⁠d/r0⁠ where d is as defined above. Replacing r0 as before yields the full Kapustinskii equation.