Dear Justin, Thanks for your answer. I know, Energy minimization causes energy to go down. For example, in following lines, I want to know what value is for step 12 or step 22 in energy minimization? > 11.000000 -91587.226562 > 13.000000 -93838.976562 or > 21.000000 -99023.460938 > 23.000000 -99470.914062