Calculated elastic constants of the α-quartz and α-cristobalite phases of BeF₂, and the rutile phase of ZnF₂.

System	Phase	Approach	Elastic constants (GPa)
			C 11	C 12	C 13	C 14	C 33	C 44	C 66
BeF2	α-Quartz	LDA	46.975	14.223	12.067	−6.401	75.287	31.745
		PBE_sol	42.278	4.991	3.760	−9.077	53.009	30.548
	α-Cristobalite	LDA	33.309	7.300	−5.087		22.487	35.810	13.731
		PBE_sol	32.589	4.839	−5.336		24.412	37.813	16.078
ZnF2	Rutile	LDA	139.442	121.550	109.127		220.673	36.583	91.826
		PBE_sol	128.470	98.717	94.547		200.902	35.523	83.001
		Expt.33	125.5	91.8	83.0		192.2	39.5	80.7