I am trying to apply "improper" to my simulation. The am using improper_style of harmonic, and from what I know, for harmonic style, I would need angle and K (which is also in units of kcal/mol-rad^2). However, I am currently using Tripos forcefield, and the K value that I have is in kcal/mol-angstrom^2, which is actually in terms of distance instead of an angle. So, I would like to know what needs to be done in order to get the improper term works in distance unit. Thank you so much for your help.