atmsel = mdl.atoms['CA:10'].select_sphere(6.0)
Where, What I have understood is: It picks atoms that comes within
mentioned A° and not all the atoms of matched residues that comes in the
mentioned A°
So, Here I want to know that Is it possible to pick all the neigbour
residues atoms within mentioned A° of the 'CA' atom is some resudue?
Sure, just extend the selection by residue, i.e.
atmsel = mdl.atoms['CA:10'].select_sphere(6.0).by_residue()
This will select all atoms in any residue that has at least one atom
within 6.0 angstroms of your original CA atom.