Table 1. Summary of the 26 Structures Investigated Here: Reporting Name, Relative Energy with Respect to Graphene, Plane Group, Pearson Symbol, sp/sp² Ratio, and Electronic Characters (Band Gap Reported for Semiconductors)^a.

name	rel. energy kcal/mol	plane group	Pearson symbol	sp/sp2 ratio	electronic character (PBE0)	refs
6-h3L	14.15	p2mm	oP12	0.50	metal	this work
6-h2L	16.81	c2mm	oS20	0.66	metal	this work
6-h2L2	20.55	p2mg	oP16	1.00	metal	this work
6-hL	20.59	p2mm	oP8	1.00	metal	this work
6-hT2 γ-GDY	21.13	p6mm	hP18	2.00	B.G. = 1.63 eV	(16−18)
6-hRL2	22.65	c2mm	oS48	2.00	0 B.G.	this work
6-hT2R	22.69	p2mm	oP28	2.50	B.G. = 0.83 eV	(17,18)
6-hL2	23.11	c2mm	oS28	1.33	metal	this work
6-hL3	24.06	p2mm	oP20	1.50	metal	this work
6-hR3	24.07	p6mm	hP32	3.00	0 B.G.	(17,18)
6-RL2	24.73	p2	mP22	2.66	0 B.G.	this work
6-RL	24.73	p2	mP16	3.00	0 B.G.	this work
6-R2L	25.03	p2	mP26	3.33	0 B.G.	this work
6-HT2L δ-GDY	25.07	p2mm	oP36	3.50	B.G. = 0.18 eV	this work
6-HT2 β-GDY	25.40	p6mm	hP30	4.00	B.G. = 1.14 eV	(16−18)
6-HL3	25.41	p6mm	hP32	3.00	0 B.G.	(18)
6-R	25.48	c2mm	oS20	4.00	0 B.G.	(16−18)
6-HR2L	25.85	c2mm	oS80	4.00	0 B.G.	this work
6-HR3	26.11	p2mm	oP44	4.50	0 B.G.	this work
6-L	26.18	c2mm	oS12	2.00	metal	(16,18)
6-HR2	26.30	c2mm	oS68	4.66	0 B.G.	this work
6-HR	26.63	p2mm	oP24	5.00	0 B.G.	(17,18)
6-H2R2	26.63	p2mg	oP48	5.00	0 B.G.	this work
6-H2R	26.92	c2mm	oS76	5.33	0 B.G.	this work
6-H3R	27.05	p2mm	oP52	5.50	0 B.G.	this work
6-H α-GDY	27.39	p6mm	hP14	6.00	0 B.G.	(16−18)

^aIn the last column, the reference number of previous papers investigating the same structure is reported.¹⁶⁻¹⁸