Table 4. Comparison of the Two-Point Extrapolation Scheme EP(m/n, τ) with τ = 3 and τ = 7 and the ICE(TGen,τ) Single-Point Energiesa.
| error
(mH) |
|||||
|---|---|---|---|---|---|
| extrapolated |
E(Var+PT2) |
||||
| τ |
τ |
||||
| EP(m/n) | 3 | 7 | ICE(TGen,τ) | 3 | 7 |
| (4/5) | 0.080(0.130) | 0.040(0.050) | 5 | 0.800(1.100) | 0.070(0.080) |
| (5/6) | 0.018(0.025) | 0.005(0.012) | 6 | 0.180(0.260) | 0.013(0.016) |
| (6/7) | 0.004(0.005) | 0.004(0.006) | 7 | 0.030(0.040) | 0.002(0.005) |
| (7/8) | 0.002(0.004) | 8 | 0.007(0.009) | ||
| cost
(seconds) |
|||||
|---|---|---|---|---|---|
| extrapolated |
E(Var+PT2) |
||||
| τ |
τ |
||||
| EP(m/n) | 3 | 7 | ICE(TGen,τ) | 3 | 7 |
| (4/5) | 898.5 | 6312.7 | 5 | 704.7 | 4407.0 |
| (5/6) | 2639.6 | 22112.7 | 6 | 1934.8 | 17705.7 |
| (6/7) | 7911.0 | 66786.0 | 7 | 5976.2 | 49080.3 |
| (7/8) | 27694.0 | 8 | 21717.8 | ||
a
The FCI21 data has been used to compute the error (in mH) between the FCI energy and the ICE/two-point EP(m/n,τ) extrapolated energies. The variance of the computed error (i.e., error bars) are given in parentheses. Timings correspond to the same FCI21 set. All results are for the CSF-ICE variant.