This visualiser follows the 1958 Pekeris ground-state helium construction directly. Each row is one truncated Eq. (22) recurrence for a basis state A(l,m,n). Each column is one coefficient A(l',m',n') in the symmetric basis. Clicking a coloured square shows exactly which shifted terms from Eq. (22) land in that matrix entry.
A filled square means the row state (l,m,n) couples to the column state (l',m',n') after the Eq. (22) shifts are truncated to l+m+n \le \omega and folded into the singlet symmetry A(l,m,n)=A(m,l,n).
Building determinant...
Click a nonzero square to inspect how Pekeris' shifted coefficients accumulate into one determinant entry.