It’s been years since I’ve seen a jazz band blow the roof off a club like Atomic can. They inject harmonically complex, pleasingly melodic postbop with pedal-to-the-metal free-jazz intensity–and they keep getting better with every album. On last year’s Happy New Ears! (Jazzland) the Swedish-Norwegian quintet throttled back a bit, allowing the empathetic interplay between the musicians to take the foreground: bassist (and Chicagoan) Ingebrigt Haaker Flaten and drummer Paal Nilssen-Love might drop bomblike accents among the taut long tones from the front line, or reedist Fredrik Ljungkvist and trumpeter Magnus Broo might crisscross the rippling accompaniment of pianist Haavard Wiik with delicate simultaneous solos. Atomic is still rooted in that special brand of 60s free jazz that wasn’t quite ready to stop swinging, but increasingly the band is exploring new polarities: Ljungkvist’s “Two Boxes Left” is brainy and frenetic, its zigzagging melody complicated by tempo shifts and weird harmonies, while Wiik’s “Soundtrack” is moody and minimalist, elevating texture and tone over melody and groove. It’d be easy to make Atomic sound like formalists who are just checking off boxes as they master various styles, but when they’re onstage their music exists as an energizing whole–all the different approaches in their compositions collide and fuse. I saw a smoking set by the group last summer in Kongsberg, Norway, and never have an audience’s spontaneous whoops and shouts seemed more appropriate. See also Saturday. a 9 PM, Green Mill, 4802 N. Broadway, 773-878-5552, $12.