UT theoretical chemistry code forum

Hi, I wonder how the dimer separation is defined (or maybe rather how it is used). Is it right that to get the coordinates of the two images in the dimer are IMAGE1 = POSCAR +.5*DdR*MODECAR IMAGE2 = POSCAR - .5*DdR*MODECAR where DdR is the dimer separation? MODECAR is suppose to be a unit vector ...