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Mean inter-particle distance (or mean inter-particle separation) is the mean distance between microscopic particles (usually atoms or molecules) in a macroscopic body. ==Ambiguity== From the very general considerations, the mean inter-particle distance is proportional to the size of the per-particle volume , i.e., : where is the particle density. However, barring a few simple cases such as the ideal gas model, precise calculations of the proportionality factor are impossible analytically. Therefore, approximate expressions are often used. One such an estimation is the Wigner-Seitz radius : which corresponds to the radius of a sphere having per-particle volume . Another popular definition is : , corresponding to the length of the edge of the cube with the per-particle volume . The two definitions differ by a factor of approximately , so one has to exercise care if an article fails to define the parameter exactly. On the other hand, it is often used in qualitative statements where such a numeric factor is either irrelevant or plays an insignificant role, e.g., * "a potential energy ... is proportional to some power n of the inter-particle distance r" (Virial theorem) * "the inter-particle distance is much larger than the thermal de Broglie wavelength" (Kinetic theory) 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Mean inter-particle distance」の詳細全文を読む スポンサード リンク
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