# Community number	#Community size	#Pacs label(s) in majority within community
0	18	78	Spectroscopy
1	34	83,68	Rheology, Surfaces and interfaces
2	76	61	Crystallography
3	7	47	Fluid dynamics
4	13	02,03,42	Mathematical methods in physics, Quantum mechanics field theories and special relativity, Optics
5	35	04	General relativity and gravitation
6	35	47	Fluid dynamics
7	65	13	Particle physics (Specific reactions and phenomenology)
8	12	52	Physics of plasmas and electric discharges
9	8	27	(Properties of specific nuclei listed by mass ranges) Nuclear physics
10	7	02,11	Mathematical methods in physics, General theory of fields and particles
11	13	52	Physics of plasmas and electric discharges
12	7	78	Spectroscopy
13	13	81	Materials_science
14	7	71	Electronic structure of bulk materials
15	7	78	Spectroscopy
16	8	87	Biological and medical physics
17	30	71	Electronic structure of bulk materials
18	7	61	Crystallography
19	14	71	Electronic structure of bulk materials
20	7 	33,78 	Molecular properties and interactions with photons, Spectroscopy
21	7 	61,72,71	Crystallography, Electronic structure, Electronic transport
22	7 	75,71	Magnetic properties and materials, Electronic structure of bulk materials
23	7 	68 	Surfaces and interfaces; thin films and nanosystems
24	7 	81	Materials_science
25	7 	02,68,82	Mathematical methods in physics, Surfaces and interfaces, Chemical physics
26	7 	46	Continuum mechanics of solids