noun
conformation
In chemistry, the spatial arrangement of atoms in a molecule that can be changed by rotation around single bonds, without breaking bonds.
シクロヘキサンの立体配座には、いす型と舟型がある。
Cyclohexane has chair and boat conformations.
立体配置 refers to configuration, which involves breaking and reforming bonds to change arrangement, while 立体配座 refers to conformation, which involves rotation around single bonds without bond breaking.
Compound of 立体 (three-dimensional) and 配座 (arrangement, configuration), likely a calque from English 'conformation' in chemistry.