For the first time since peace talks opened here last Monday, President Clinton sat down to dinner tonight with Israeli Prime Minister Ehud Barak and Syrian Foreign Minister Farouk Charaa, seeking to soften half a century of hatred with casual conversation, beef tenderloin and wine.

The informal dinner produced no reports of breakthroughs in negotiations that by all accounts remain agonizingly slow. But it did contribute to an impression of modest progress at the talks, which could start winding down Monday after the planned departure of Barak and possibly Charaa.

Earlier today, Israeli and Syrian negotiators passed another milestone when they confronted the pivotal question of how far Israel is willing to withdraw from the Golan Heights. Until today, Barak had resisted that discussion, arguing that Israeli negotiators could not grapple with the question of a Golan withdrawal without knowing more about Syria's willingness to protect Israel's security and water resources.

At a briefing, State Department spokesman James P. Rubin said the two sides also had begun making refinements to an American-drafted "working document" that spells out areas of agreement and dispute and could become the basis of a final peace settlement. But he said that "it's a little early" for U.S. mediators to offer "dramatic bridging proposals" and reiterated that the current talks are unlikely to produce a "core agreement."

"The decisions being contemplated here . . . are enormously portentous," Rubin said. "We don't expect these decisions to be made in a matter of days."

On Saturday, negotiators took most of the day off in observance of the Jewish Sabbath and the Muslim holiday Eid al Fitr. Charaa shed his tie to take tea with Secretary of State Madeleine K. Albright at her farm in nearby Hillsboro, Va. This morning, Albright accompanied Barak, his wife and Israeli Foreign Minister David Levy to Antietam National Battlefield, where the bloodiest day of the Civil War occurred, before going to Harpers Ferry, where John Brown led an unsuccessful slave rebellion.

Israel Radio reported that Barak and Charaa had exchanged pleasantries when they bumped into each other at the gym. Clinton and his team attach considerable importance to such informal contacts. "I think the president believes it's important to bring the leaders together in a number of different settings to try to bridge the differences," White House spokesman Joe Lockhart told reporters.

But real work was also being done today. Besides the meeting of the border committee, negotiators also sat down for discussions on security arrangements and the nature of future relations. A Syrian delegate told an Arab journalist that today's meetings marked the beginning of "the serious bargaining," the journalist said.