Dear Chimera, I have been facing a problem recently while using UCSF Chimera. After opening the structure of ligands in the chimera window as .pdb file, when ever I am trying to minimize the energy (Tools-->Structure Editing-->Minimize Structure) of that ligand in (which is in .pdb form), I am getting the following error message: "Failure running ANTECHAMBER for residue". I am using "AMBER ff14SB" (for standard residues) and "Gasteiger" (for other non-standard residues). Upon trying out with "AM1-BCC" (for other non-standard residues), I am getting an altered compound so that cannot be perhaps tried. Kindly find attached the .pdb files for the ligands I am trying to minimize the energy, and a word file containing the screen shots of the step-by-step messages leading to the error message that I am getting. I will be highly grateful if you can help me in sorting out the problem. Thanks in advance, Best Regards, *Prabuddha Bhattacharya * *Assistant Professor* *Adamas University* *Kolkata 700126* *India*