Predicting crystal habits under the influence of additives by means of molecular modeling software (e.g., Cerius(2)) requires additionally models in order to find the final crystal habit. Here, Periodic Bond Chains (PBC-vectors), are used to improve the results of one of these model approaches, the build-in approach [1,2]. The build-in approach does not always produce the desired results. A computer program was developed to find the PBCs and to investigate their changes as a result of the presence of additives. This approach is verified using the examples of benzophenone with different additives. Furthermore, the results are discussed and problems are highlighted.