From: Bin Sun (
Date: Sun Jan 15 2017 - 18:36:22 CST

Hi All,
I want to use the cv module of VMD to calculate the alpha-helical content
of a peptide(24 residues). I first loaded the pdb file and then open the Tk
console. The following content was typed into the console:
cv molid 0
cv config {
  colvar {
     name alpha_content
     alpha {
       residueRange 1-24
However, the above command does not give the right result, instead, en
error message appeared saying "Error: could not find atom "O" in residue
XX(1-24), segment "MAIN" ". I doubled checked the pdb file and be sure that
no atom is missing.

Could anybody give some advice about this error ?

Thanks in advance !