President Obama has named Virginia Technology Secretary Aneesh P. Chopra to be the nation's first chief technology officer. The president announced the choice over the weekend in his weekly radio and Internet address, adding Chopra to a small group of advisers whose aim it is to enhance and modernize the delivery of government services. The president also named Jeffrey Zients, a chief executive and former management consultant, to be his chief performance officer. The position was initially offered to Nancy Killefer, who withdrew after questions were raised about her payment of taxes. Chopra, appointed by Virginia Gov. Timothy M. Kaine in 2006, had been under consideration for months for a job in the Obama administration, including technology chief at the Department of Health and Human Services.