The application of the λ parameter method to calculation of the interaction energies between two plane parallel double layers for symmetric electrolytes

The lambda parameter method had successfully been applied to calculate the interaction energies between two plane parallel double layers for symmetric electrolytes. When y(0) and |y(d)|<= 20, the number of the series terms required to obtain the interaction energies with six significant digits is not more than 4. If we regard the interaction energies as the function of the hyperbolic function tanh (y(0)/2) instead of tanh(y(0)/4), then calculating it with the aid of lambda parameter method, we can obtain above results at once. This enables one to avoid the mathematical complexity of other methods.