Numerical details

All calculations presented below were done by using the code HFODD [26,37], version (2.48q) or higher, which includes both the angular-momentum and isospin projections. In order to obtain converged results for isospin mixing with respect to basis truncation, in our SV calculations we used $N=10$ harmonic oscillator (HO) shells for $A < 40$ nuclei, 12 shells for $40 \le A < 62$ nuclei, and 14 shells for $A \ge 62$ nuclei. In SHZ2 test calculations, we took $N=10$ shells for $A < 40$ and $N=12$ shells for $A> 40$ nuclei.

For the numerical integration over the Euler angles in space and isospace ( $\alpha, \beta, \gamma ; \beta_T$) we used the Gauss-Tchebyschev (over $\alpha$ and $\gamma$) and Gauss-Legendre (over $\beta$ and $\beta_T$) quadratures. We took $n_\alpha = n_\beta = n_\gamma =20$ and $n_{\beta_T} = 8$ (or 10) integration points. This choice guarantees that the calculated values of $\delta_{\rm C}$ are not affected by the numerical integration error.