As it was proposed by Prof. Granovsky I would like to share my small ideas :
1. An efficient scan method considering one or more bonds and angles would be useful to facilitate finding transition states. One may want to OPTIMIZE the system through a scan procedure or calculate ENERGY (only SCF) so both options seems to be helpful. Also, It would be very great for us if Firefly writes a Table including the ENERGY vs. "scan parameters" at the end of the scan procedure, because it facilitates data processing and finding the transition state by visualizing the data.
2. Including more internal basis sets and ECPs can facilitate running a job.
3. There are some useful free codes such as "POLYRATE 2010" of Donald G. Truhlar that was in interaction with some electronic structure codes and can be useful if it is possible to be included. Also some new DFT functionals have proposed by Truhlar group which have advantages.
4. Analytic hessian calculation for restricted and unrestricted systems is our wish.
5. NBO charges, spins and etc can not be easily read and shown by standard visualizing softwares which are related to Firefly.
6. If "combo" can facilitate SCF convergence problems, is it possible to include it or some other magics in Firefly (internally) to solve the problems.
7. Introducing more example files seems to be helpful.
8. Sometimes it is useful to fix Cartesian coordinates instead of fixing bonds or angles. Especially if it is possible to fix one or two or all of the components of Cartesian coordinates. For instance one may want to fix x and y of atom #36 and x,y and z of atom #60.
I hope the best for Firefly !
Masoud Nahali, Sharif University of Technology