【摘要】 我们已经推导出一个电介质方程，在方程中电介质的密度能够由介电常数算出。麦克斯威关系是联系非极性电介质的介电常数ε和折射系数ｎ的表达式。利用麦克斯威关系，我们把这个非极性电介质方程推广到光频区域并获得相应公式，这个公式是在电介质的密度和折射系数之间建立了联系。我们把它称为一种改进了的劳仑茨一劳仑兹方程，也就是本文中的方程（７）。方程（７）中有三个参量，它们能够通过和实验数据进行比较来确定。氢是最常见的电介质物质，它有完善的实验数据，其中包括密度和介常数。仲氢的方程（７）中的参量值通过和实验数据比较而求得，并把它们列在文中方程（９）中。方程（１０）是关于仲氢的改进了的劳仑茨一劳仑兹方程的形式。从方程（９）我们能够确定平均极化率和分子半径。氢的平均极化率为０．３９８×１０－２４ｃｍ３，分子半径为２．０４×１０－８ｃｍ。它们和实验值是同一数量级。这样，首次由折射率来求得分子半径。另一方面，仲氢的密度可以由公式（１０）来计算。在密度范围从０．００２ｇ／ｃｍ３到０．０９６ｇ／ｃｍ３区域内，计算结果是极好的。它和实验值的偏差小到只有１０－６数量级。然而，由著名的Ｂｏｅｔｔｃｈｅｒ公式和劳仑茨—劳仑兹方程计算的结果，和实验?更多还原

【Abstract】 We have derived an equation on non polar materials, in which the density of the material may be calculated from its dielectric constant accurately. The Maxwell relation is an expression that relates the dielectric constant ε with its refractive index n for non polar dielectric material. Using the Waxwell relation, we extrapolate the non polar dielectric equation to the light region to get a formula. It relates the density to the refractive index, called as an improved Lorentz Lorenz formula, i.e.equation (7). There are three parameters in the equation (7). That may be determined by a comparison of experimental data. Hydrogen is one common dielectric material, which has a perfect data including both density and refractive index. For parahydrogen, the values of parameters in equation (7) are determined by the comparison and listed in the equation (9). The equation (10) is the improved Lorentz Lorenz equation for parahydrogen. From equation (9), we may determine the mean polarizability and the molecular radius. The former value is 0.398×10 -24 cm 3 and the latter is 2.04×10 -8 cm. They agree with the experimental results in the same order. This is the first time to get the molecular radius from the refractive index. On the other hand, the density of the parahydrogen may be calculated by the formula (10). In the region where the desnity ranges from 0.002g/cm 3 to 0.096g/cm 3, the calculated results are extremely good. Its deviation is as small as an order of 10 -6 . However, the deviations calculated by both the famous Boettcher and Lorentz Lorenz formulae are much higher than those of our results, and especially in the dense region they reach as large as an order of 3×10 -4 . Their deviations are a hundred times larger than ours. In summary, we may obtain the molecular radius of a dielectric from its refractive index and calculate density from refractive index with great accuracy. Therefore, the equations (7) and (9) can be thought successful ones.更多还原