액체이론(Significant Structure Theory)를 단원자 분자로부터 다원자 분자에 이르는 여러 액체혼합물에 적용하여 전 농도 범위에서 액체 혼합물의 활동도 계수를 계산했다. 단원자 분자계(Ar-Kr, Kr-Xe)와 이원자 분자계$(Ar-O_2,;N_2-CO)$와 메탄-크립톤계의 액체혼합물의 활동도 계수는 ${delta}E_s$ 수정 변수에 의해 좋은 결과를 얻었다. 아르곤-질소, 산소-질소, 그리고 메탄-프로판계에 대해서는 이 외에 ${delta}$V, ${delta}$n 수정 변수가 더 필요했다.
Significant structure theory was applied to some liquid mixture systems ranging from simple monatomic molecule systems to polyatomic molecule systems, and the activity coefficients ${gamma}$ of the liquid mixture systems were calculated over whole mole fractions using the following thermodynamic relation $RTln_{{gamma}i} = (frac{{partial A}^E}{{partial N}_i})_{T,V,N_i} $ where $A^E$ represents the excess Helmholtz free energy, and $N_i$ is the number of molecules of component i. The activity coefficients of the solutions such as monatomic molecule systems (Ar-Kr, Kr-Xe) and diatomic molecule systems $(Ar-O_2,;N_2-CO)$ and $CH_4-Kr$ systems whose components have similar shapes for intermolecular potential curves were calculated successfully only with the ${delta}E_s$, correction parameter for energy $E_s$, for mixture systems. For other systems such as $Ar-N_2,;O_2-N_2;and;CH_4-C_3H_8$ whose components have dissimilar intermolecular potential curve shapes an additional correction parameters ${delta}$V and even one more parameter ${delta}$n were necessary [see Eqs.(10)∼(12)].
