Table 2. Comparison of the unit-cell parameter a and interionic distances (Å) in the structures of grossular obtained experimentally (synchrotron and in-house diffractometer) and theoretically (TRi, i = 1–5).

Computations without a set external pressure are marked with n/a.

	Exp_1GPa	TR1	Exp_Amb	TR2	TR3	TR4	TR5
p (GPa)	1.00 (1)	n/a	Ambient	n/a	n/a	1.0	10.0
a	11.8799 (1)	11.8799 (1)	11.8588 (1)	11.8588 (1)	11.8295 (1)	11.8080 (1)	11.6320 (1)
Ca—O′	2.3303 (4)	2.3276 (2)	2.3257 (2)	2.3263 (2)	2.3218 (2)	2.3184 (2)	2.2913 (2)
Ca—O′′	2.4912 (4)	2.4910 (2)	2.4892 (2)	2.4840 (2)	2.4745 (2)	2.4674 (2)	2.4099 (2)
Si—O	1.6513 (4)	1.6595 (2)	1.6466 (2)	1.6579 (2)	1.6555 (2)	1.6539 (2)	1.6397 (2)
Al—O	1.9319 (4)	1.9236 (2)	1.9288 (2)	1.9194 (2)	1.9149 (2)	1.9115 (2)	1.8843 (2)