Table 1 Details of the convergence of the X2C-CASCI calculation (100 2-spinor orbitals, 88 electrons, 1015 2-spinor determinants) of the ground state of HBrTe (x2c-TZVPall96)

From: Numerically exact configuration interaction at quadrillion-determinant scale

Iteration

Duration (s)

Active Energy (Eh)

ΔE (Eh)

\(\max \{| \Delta {C}_{i}| \}\)

r (Eh)

1

122

−9812.080102321897

− 

− 

2.62 × 10−1

2

111

−9812.129587025540

4.95 × 10−2

5.45 × 10−2

8.73 × 10−2

3

262

−9812.133341658482

3.75 × 10−3

1.36 × 10−2

3.23 × 10−2

4

710

−9812.133735698319

3.94 × 10−4

2.26 × 10−3

1.40 × 10−2

5

1536

−9812.133784486688

4.88 × 10−5

1.08 × 10−3

7.14 × 10−3

6

3293

−9812.133790409140

5.92 × 10−6

4.97 × 10−4

4.09 × 10−3

7

6432

−9812.133791245860

8.37 × 10−7

1.31 × 10−4

2.54 × 10−3

8

11,565

−9812.133791408300

1.62 × 10−7

9.17 × 10−5

1.61 × 10−3

9

20,384

−9812.133791451150

4.28 × 10−8

4.25 × 10−5

9.71 × 10−4

  1. Each row corresponds to a Davidson iteration. The fourth and fifth columns track the changes in the computed Rayleigh-Ritz eigenpair across iterations, and the sixth column tracks the residual norm, r = HC − EC, where H is the Hamiltonian, C is the CI vector, σ is their product, and E is the corresponding energy. The preconditioning dropping threshold was taken to be ε = 1.0 × 10−5. The inactive energy is 417.105787 a.u.