Development of a transferable force field between MOF and its polymorph

Abstract

Force fields for metal-organic frameworks are widely used for classical mechanics as they can be utilized to get many chemical properties. Although some force fields were developed to be applied universally, deviations from the genuine values still occur when we use these fields in uncommon systems. To deal with this problem, developing a new force field using quantum mechanics is required. However, this method is often undesirable in that the computational cost for DFT calculations increases dramatically as the size of a system increases. Therefore, we decided to devise a method to reduce gratuitous calculations

finding transferability from a smaller polymorph of MOF to the original one. With compatibility, one might develop a force field in a smaller system and use it at a lower cost. In this research, we have developed force fields for a small polymorph of MOF-177. It was accomplished by adjusting force field parameters so that binding energies from classical calculation could match the values from the quantum calculation. Then, by checking whether the new force field can reproduce the accurate chemical properties in the original MOF-177, we figured out that force fields are transferable in polymorphs of MOF-177. In addition, as the efficiency of the new force field enhanced regardless of charges, we can conclude that transferability is noticeable in diversely charged systems.