Reaction Design, a San Diego developer of chemistry simulation software, said it entered into a definitive merger agreement with Ansys Inc., a Pittsburgh maker of engineering software.

Financial terms of the proposed transaction, which is expected to close in January, were not revealed. The parties said management will provide more details subsequent to the closing.

Reaction Design’s software allows transportation manufacturers and energy companies to achieve clean technology goals by automating the analysis of chemical processes through computer simulation and modeling solutions, the company said.

Jim Cashman, Ansys CEO, said Reaction Design has helped companies in a variety of industries to better understand chemical processes involving engine and fuel efficiency. “Combining its solvers with Ansys’ solutions will give customers new insights into the combustion processes in their products driving increased fuel efficiency,” he said.

Reaction Design said it serves more than 400 customers worldwide.