. 2022 Oct 24;3(11):100609. doi: 10.1016/j.patter.2022.100609

Table 1.

A comparison of several Ca-containing materials

Material	X	Involved orbitals	E_orb (eV)⁶⁰	d_Ca-X (pm)⁵⁹	r_X (pm)^a	λ (pm)	T_c^max (K)
CaO	O	Ca 3p – O 2s	−29.17	239	140	0	N/A
Ca (ambient pressure)	Ca	Ca 3p – Ca 3p	−33.77	395	99	197	N/A
CaLi₂⁵⁶	Ca	Ca 3p – Ca 3p	−33.77	383	99	185	13
Ca (216 GPa)^b	Ca	Ca 3p – Ca 3p	−33.77	231^c	99	33	29
Bi₂Sr₂Ca₂Cu₃O_10-x^d	O	Ca 3p – O 2s	−29.17	252	140	13	110
HgBa₂Ca₂Cu₃O_9-x⁵⁷	O	Ca 3p – O 2s	−29.17	236	140	−3	134

“X” represents the neighboring atom of Ca. E_orb is the energy level of the involved orbital in X. d_Ca-X is the bond length. r_Ca and r_X are ionic radii of Ca and X, respectively. λ = d − r_Ca − r_X is a characteristic parameter for the Ca–X bond.

Pauling ionic radii.

Hamlin.⁶¹

DFT simulated value.

Chu, et al.⁶²