Plenty has been written about the intersection—past and present—between members of the Swedish/Norwegian collective Atomic, and Chicago's Ken Vandermark's countless projects. Most telling, perhaps, is this simple fact: were Atomic American-based, there's little doubt it would garner similar accolades from a considerably larger audience unafraid of the kind of fearless experimentation that's been the quintet's signature since convening around the turn of the millennium. Retrograde is the group's fifth release and second three-CD set, following its all-live The Bikini Tapes (Jazzland, 2005). With two discs of new studio material and a very recent (June 2008) live set from Seattle, Atomic continues to mine its unique meeting place of American-centric free jazz, Scandinavian melodies and a personal approach to composition-cued spontaneity.

Despite the majority of writing penned by reedman Fredrik Ljungkvist and pianist Havard Wiik—whose trio disc, The Arcades Project (Jazzland, 2007), is another fine example of Scandinavian artists reinventing an aging format—Atomic remains a democratic affair, with additional compositional input from trumpeter Magnus Broo and bassist Ingebrigt Haker Flaten. Drummer Paal Nilssen-Love may not contribute any material, but his ability to tread the line between diverse texture and unabashed, unfettered swing—sounding as Tony Williams might have, had he brought his growing interest in rock energy to the free bop of Miles Davis' mid-'60s quintet—remains a key component of the Atomic sound. The added energy that comes from playing before an audience turns the live version of Broo's relentless "Painbody" into an eight minute encapsulation of what Atomic is, but the briefer studio version is no less potent, no less...atomic. This is no introverted music informed by stark Scandinavian landscapes; this is urban music, filled with energy and a paradoxically controlled abandon that teems with excitement and acute interaction.

Everyone in Atomic is a leader, making the distinct collective identify of Atomic all the more remarkable. Ljungqvist's "Db Gestalt" is a jagged confluence of contrapuntal melodies, leading into a free section where his visceral baritone sets up a characteristically architectural solo from Wiik, with Broo's probing, initially lyrical but ultimately more far-reaching solo, periodically bolstered by the tune's time-staggered theme. Wiik's title track is Atomic's version of beauty: spare, with its own angular lyricism, leading into another intensifying free-for-all, where Ljungkvist's sinuous clarinet contrasts with Broo's raspy horn. Contemporary classicism meets spontaneous invention on Wiik's "Invisible Cities," where cued melodies are broken up by spare, coloristic interjections, with Nilssen-Love at his most abstract.

Less compositionally cerebral than The Vandermark 5, Atomic still shares much in common with Vandermark's highly acclaimed flagship group. Double-disc sets are risky, triple-disc sets almost unheard of outside of compilations and archival reissues, but Retrograde proves that Atomic has what it takes to sustain itself across three CDs and over two-and-a-half hours of music. The group continues to evolve a stunning contrast in sound that juxtaposes power with nuance, aggression with oblique calm, and unapologetic freedom with rock-hard, visceral groove.