They call him Slava. In white tie and tails, he strides briskly across the stage at the Kennedy Center, raises his baton, and plunges the orchestra into a performance of ''The Star-Spangled Banner'' that's so exuberant that the crystal chandeliers seem to shake. At ''the land of the free'' he summons up a golden crash of cymbals like an exclamation mark.
He has entered the country - music - from which he can never be exiled.
Mstislav Rostropovich, stripped of his Soviet citizenship five years ago - at the height of a career as cellist which won him the Lenin Prize, the Stalin Prize, and the nation's top honor, People's Artist of the Soviet Union - is scoring a new life here as conductor and music director of the National Symphony Orchestra.
Rostropovich, of medium height, has crystal blue eyes behind black-rimmed glasses and a half-thatch of pearl-gray hair framing an expressive face. He has been rehearsing the Sibelius Second Symphony, working out as strenuously as a boxer in preparation for a tour with the orchestra to Texas, New Mexico, Nevada, and California. But for a lunchtime interview he has changed from his conductor's clothes (drenched from the rehearsal) to a blue-gray tweed jacket, finely striped blue and white shirt, blue silk tie, and flannel trousers.
He talks in fluent Russian, thick and pungent as borsch, and prefers to have his executive assistant, Nadia Efremov, translate into polished English sentences his reflections on what some would call a life of ''creative exile.''
''My connection with my people has been strengthened,'' he says, speaking of that exile, ''because I think that with these actions, not just toward me but toward other artists, the Soviet government removes itself even further from the people.''
He doesn't look like a criminal. But in the USSR, fraternizing with Rostropovich is considered a criminal act. Such an attitude by the Soviet government ''doesn't take us away from the people,'' he explains; ''it just removes itself. I didn't stop loving my people. I devote all of my time to music and still keep trying to help all the people who are in need of help whom we meet. And I've become more deeply religious since that time. I'm very satisfied with my life, which is full of music, work, and now full of friends.''
It's an attitude he shares with other exiles. ''Despite the fact that we are nostalgic for the Soviet Union,'' says Maxim Shostakovich (the composer's son), ''we have found our second home.''
Victoria Mullova, a violinist whom Rostropovich championed at a press conference here when she defected from the Soviet Union in July, agrees. She says that under the Soviet government ''my career was pushed down all the time'' and that ''I had only a few concerts. Here I can choose what music to play, and I can record music.''
The ''criminal'' Rostropovich and his wife (Galina Vishnevskaya, the celebrated soprano) left the Soviet Union on an exit visa in 1974 - when, as he once said, ''I did not exist as an artist'' anymore. The Soviet government had banned their concerts abroad and put them in ''artistic quarantine'' because they had defended writer Alexander Solzhenitsyn and sheltered him in their home.
Clearly, the quarantine didn't work. Rostropovich is still often called the world's greatest cellist. And as a conductor, he is ''mercurial,'' writes Joseph McLellan, a Washington Post music critic. ''Rostropovich the conductor must still be considered a promising talent - often brilliant, always unpredictable.'' McLellan adds that Russian music seems to bring out Rostropovich's genius. Audiences and critics agree that Rostropovich has enriched and burnished the sound of the National Symphony, augmenting it with new talent.
Rostropovich says that ''when I conduct, I conduct because I feel that particular way. . . . The only thing I can say is, I cannot live without this music. . . . And only one thing has to be taken into consideration, that I remain that same personality with the same convictions as a cellist, as a conductor, as an accompanist, as a musician. I don't think it can be said of me that I know how to play Beethoven on the cello and do not understand how to conduct Beethoven. Because that's (the) same composer, same music, same point of view.''
Pianist Eugene Istomin, after an arduous 31/2-hour rehearsal with Slava, says of his friend that ''he has a great affinity for Russian music.''
''But,'' he adds, ''he's a great musician, and you can't nationalize or generalize about someone whose talent is universal. . . . He's got something he brings to all music, a colossal temperament. . . . He projects very powerfully, with that intensity he brings to everything.''
That intensity, even after years of exile, is still distinctly Russian. For despite the fact that his daughters, cellist Olga and pianist Elena, have become Americanized as graduates of the Juilliard School of Music in New York, his Russian roots are deep. Born in Baku, Azerbaijan, to a cellist father and pianist mother, he began to compose and play the piano at age 4. At 8 he took his cello to Moscow's Children's Music School. His composition teacher at the Moscow Conservatory was his mentor and friend, Dmitri Shostakovich.
When he lost his Soviet citizenship five years ago, Rostropovich decided that ''now that I am without my Russia, I would like to have my own Russian island.''
So he began collecting Russian art, porcelains, icons. Since then, he says, ''I have accumulated a few more islands, and I keep adding to my islands all the time. When I see something beautiful, Russian-made, my heart starts to flutter like a bird.''
With homes now in Paris and Switzerland (he travels on a Swiss passport), Rostropovich has also bought yet another Russian island: an American dacha in Jordanville, in upstate New York, near his favorite Russian Orthodox monastery. Russian liturgical music is as dear to him as his cello; he hopes to hold a series of concerts or symposiums for choirmasters at the monastery.
Rostropovich speaks with passion of the destruction of the religious musical heritage under the Soviet regime. Once, he says, ''All of Russia sang'' in church choirs. Nowadays, he explains, a few churches and cathedrals with choirs exist for government propaganda purposes. Of his own credo, he says simply that ''I believe in Christ. I'm absolutely convinced in the existence of a higher power, absolutely convinced in the existence of life after death. I can't describe them to you, but I think that no one else can, either. . . . I think we can feel with our intuition what it is.''
That's a side of the man Washington audiences rarely see. They have, however, seen other sides, both on and off the podium. He once did the bunny hop with the audience after conducting a Fourth of July concert on the Capitol lawn. He dressed up as Haydn - in velvet knee breeches and wig - for a Leonard Bernstein birthday version of ''the Toy Symphony.'' And this fall he stretched out an intermission like an accordion to autograph new National Symphony records in the lobby for hundreds of fans. ''I have to love the people in order to make good music,'' he says.
What lies ahead? He's scheduled to take a sabbatical from his frenetic schedule next year, but he says that ''the sabbatical looks like a shipwreck at this point.''
As for the orchestra tour, he says he loves ''the scope of America.'' It reminds him of Russia. ''I see these immeasurable dimensions,'' he explains, ''and you see a tremendous power in it. Traveling down the highway, you have the feeling that for as much time as you have, you can keep traveling down that highway.''