On the second floor of Zimbabwe's Parliament building is a small, functionally equipped corner office, barren of personal memorabilia. A visitor asks its occupant if he has been asked to perform any special task for Zimbabwe's new prime minister, Robert Mugabe.

"Well, we meet quite often and we seem to have an ability to communicate with one another, even though it's not what my thoughts are or what my task is," replied Ian Smith in slow, deliberate words. As the former prime minister speaks, his hands are grasped in his lap and his gaze fixed directly on his questioner.

Smith appears to have come to terms both with Mugabe (whom the white leader formerly never referred to other than as a "Marxist terrorist" or a "puppet" of communist powers) and with Mugabe's ideology.

"I think socialism in moderation and a mixture of socialism and private enterprise is perfectly acceptable," he said. "Speaking as a realist, I say that. In this part of the world, I think we've got to accept this kind of thing."

For his part, Mugabe appears to have dropped plans, announced during the seven-year guerrilla war, to bring Smith and his officials before tribunals for their "war crimes."

Smith led Rhodesia's white-minority population in its unilateral declaration of independence 15 years ago and then, under the duress of a guerrilla war and international isolation, brought it back to Britain's colonial fold to accept a black-majority government. This, Smith once vowed, would never happen in Rhodesia in a thousand years.

No longer first among equals, Smith is now one among 100 members of Zimbabwe's National Assembly where, at the head of his 20-man, all-white bloc, he sits opposite his second successor and long-time foe. Mugabe has never publicly criticized Smith, much less arrested him for "war crimes."

The two men did not meet until a few days before last February's British-held elections. "I did not know him at all," said Smith. "Prior to the last election, I had only met him across a conference table. I had never spoken to him.

"I was agreeably surprised once I started meeting the man, at his ability, his grasp of the situation and what appeared to me to be his straight talking. So far, from my contacts with him I have been impressed with the man's performance."

And the Smith who always cast black nationalists' demands into the all-inclusive category of "communist" is today more discerning on Mugabe's economic policies and whether they can be acceptable to whites.

"It just depends on how far we have got to go. If we go too far, then I think we will ruin this country. If the government is sufficiently astute, capable and if they don't overplay their hands, I think we can still have the greatest country on the African continent. But it will take us time.

"Many of these people -- I'm now speaking about the leaders -- say there're not communists or Marxists or any other kind of 'ists', [that] all they want to do is what is best for their country.

"On the other hand, there are some wilder comments who make irresponsible and provocative statements. The majority of these people I think would openly claim they are Marxist.

"We'll know for sure one of these days.

"I'm not quite sure what the government is trying to implement, but from what Mr. Mugabe has said, I find this quite acceptable. But whether he is going to succeed in getting his government to implement this . . .," Smith said, his voice trailing off.

In his attitude to Zimbabwe's new leader, Smith has joined most of his fellow whites. They have instinctively shifted from Smith to Mugabe as the new center of political gravity, and, as such, their protector against more radical black officials.

Smith's open-ended remarks and relaxed demeanor in the recent interview contrasted with the stiff, unemotional manner and repetitive, pat answers to questions, no matter what the occasion, that marked his contacts with the press during his years as prime minister.

After Mugabe's landslide victory last February. Smith visited him to say that he and his party would "cooperate constructively with him and his government to make a success of the future for our country."

Smith says he did not ask for and is not disappointed about not getting a Cabinet appointment. "In fact, I believe it would have been wrong to have me in the Cabinet and I have got a feeling I even mentioned this to [Mugabe] but I'm not sure," Smith said.

"If I had been given the choice to nominate some of my people I would not have nominated myself, I would have nominated some of the younger people who have their lives before them.

"Secondly, there is no denying the fact that I have been a pretty controversial figure in politics and as such, in a goverment like this, I might have been an aggravating factor. Not might have -- probably would be," Smith said.

Smith says he intends to remain in Zimbabwe and run his farm in Selukwe where he raises cattle and grows corn. "It is my home, everything I have is in this country and it's a beautiful country. I haven't yet found a place that I would rather live in than my own country," Smith said.

He would only contemplate leaving "if conditions under which we live became intolerable. If, for example, there was a breakdown in law and order [or] there was such a deterioration of standards, the things which affect one's personal life, if one's freedom was interfered with. Those are the kinds of things I think that would make myself and most white people seriously consider if they could go living here."

Despite his desire to slip away to his farm, Smith said he has "too much to do here on the political scene in Salisbury. I can't get away from it as easily as I thought and this is because of the tremendous problems which now confront the white people who are, q uite frankly, a bit bewildered."

Smith had praise for Mugabe and his ministers' "conciliatory tone," their dedication to "nonrecrimination and harmony," their "appreciations of the practicalities of life" as well as the "responsible manner" in which they have governed so far.

But he said all this was jeopardized by remarks by some of Mugabe's ministers, "the wild boys of his show" as he called them, who "talk about the terrible things of the past, about what the colonialists did, what the previous white regime did. What they conveniently forget, of course is all the good things which were done."

Though Smith concedes these people are a minority, he says they are giving impetus to white emigration. "This government has only been in a few months and people are prepared to give it a try, [but] my apprehension is that at the end of the year we're going to see a very big jump [in emigration]. Certainly from talk and information there is a tremendous buildup of people who are planning to go, tremendous. I hope it is exaggerated," Smith said.