The self-assembling conditions of 4C10Sn clusters in Ge-rich CxSnyGe1 - x - y (0.01 < x < 0.03, 0.005 < y < 0.081) dilute alloys are represented. 4C10Sn clusters are carbon tetrahedrons surrounded by Sn atoms. The considerable decrease of the internal strains is a cause of self-assembling. High density of 4C10Sn clusters may be obtained up to 800 degrees C. The majority of carbon atoms are in 4C10Sn clusters at 800 degrees C if the carbon content is less than, equal to or several times more than that of Sn. 1C4Sn tetrahedral clusters with insignificant density should also form. These theoretical results open up the possibility to produce CxSnyGe1 - x - y dilute alloys with a desired density of 4C10Sn clusters. (C) 2015 Elsevier B.V. All rights reserved.