In April 1993, Micromeritics introduced a software package called DFT V1.00. This program was the first commercial offering of a practical method to routinely analyze experimental adsorption isotherms using methods based on modern theoretical physical chemistry. It was the culmination of an investigation by James P. Olivier and William B. Conklin into a method by which the power of DFT could be utilized by any researcher or laboratory technician having only a typical desktop computer.
The challenge was to manage the vast number of iterative calculations required to generate the theoretical isotherm that best reproduced the experimental data, a task that could require days to perform on desktop computers of the day, the most modern of which were 33/66MHz machines. The solution was to divide computational tasks between a supercomputer and a desktop computer. The former would calculate sets of model isotherms, which subsequently were stored on disk. Each set was for a unique combination of the type of the gas molecule, the substrate, the temperature and the pore geometry. Each model isotherm in a set was generated by stepping through each size class in the size range for each value of relative pressure from very low values to saturation.
Then, using these models, the less laborious and more often required task of fitting a combination of model isotherms to the experimentally obtained isotherm was relegated to the desktop computer. By this allocation of computing tasks, a data reduction application employing density functional theory became available to any researcher or laboratory technician.
The Forward section in Micromeritics’ DFT V1.00 user’s manual released on April 15, 1993 contained the following prophetical statement:
“We expect that DFT, like any pioneering development, will evolve. Additional adsorptives, sample temperatures, pore geometries and substrate chemistry models will be added to the model library. Future releases of DFT may incorporate new theoretical refinements and will, therefore, not be guaranteed to produce precisely the same answers as this, the first version, when applied to the same data. It is our intention, however, to improve subsequent releases in underlying theoretical structure, in completeness of data analysis and presentation, and in ease of use. We at Micromeritics feel that this release of DFT puts a powerful tool in the hands of those who would use adsorption isotherms to characterize materials. We welcome your comments.”