Sunnyvale, Calif.--Ariba said Tuesday that Larry Mueller has been hired as COO. Mr. Mueller, previously CEO at the 3-D modeling venture Rasna Corp., takes over corporate marketing responsibilities from Ariba CEO Keith Krach. Ariba produces online catalogs and transaction systems for Fortune 500 companies. ``With his expertise, it is clear [Mr. Mueller] will be able to better position Ariba to large enterprise customers, especially in vertical markets they haven't yet tapped,'' said Albert Pang, research analyst at International Data Corp. High-tech was a market Mr. Pang identified as ripe for the picking. Mr. Mueller has also worked for J.D. Edwards & Co. and IBM Europe.