Table 1.

The electrostatic solvation energy (ΔG_el) of barstar (PDBid: 1B3S) computed with the Adaptive Poisson-Boltzmann Solver (APBS) and CPB, with and without least-squares reconstruction (LSR) and on adaptive Cartesian and uniform grids. These calculations used a 2 Å Stern layer, a convergence tolerance parameter of 10⁻⁶ and the grid side length was set to twice the longest dimension of the molecule, but otherwise were performed as described in the Methods.

Grid# spacing (Å)	Adaptive Cartesian Grid				Uniform Grid
		ΔGel (kcal/mol)	Number of Grid Points	CPU Time (s)	CPB ΔGel (kcal/mol)	APBS ΔGel (kcal/mol)	Number of Grid Points	CPU* Time (s)
0.0625	LSR	−1592	7.4×107	15735	—	—	—	—
	No LSR	−1592	7.2×107	15570
0.125	LSR	−1591	1.1×107	1318	—	—	—	—
	No LSR	−1592	1.0×107	1211
0.25	LSR	−1590	1.6×106	162	−1593	−1612	1.4×108	1048
	No LSR	−1593	1.5×106	142
0.5	LSR	−1582	2.7×105	24	−1620	−1663	1.7×107	120
	No LSR	−1620	2.4×105	19
1.0	LSR	−1546	5.8×104	6	−2097	−1706	2.1×106	19
	No LSR	−2097	5.1×104	4

—, Calculations on uniform grids could not be performed for these grid spacings because doing so would have required more than the available memory.

^*These CPU times are those found for the APBS calculations. The CPU times for CPB on the same uniform grid were significantly longer than those for APBS because CPB is optimized to use an adaptive Cartesian grid.

^#The finest grid spacing was used for the adaptive Cartesian grid.