Hello, I am trying to calculate free volume of polymers using two methods. The first one is using a script I modified based on one script found in the forum. The lines for calculate free volume of Connolly surface with r=0 is shown below. Another method I tried is in tools--> Atoms Volumes and Surfaces, and I also set the Connolly surface with r=0. But the two methods gives me quite different results. The script gives me free volume % ~ 12%, while the Atoms Volume and Surfaces tool gives me free volume percentage of >30%. Can anyone help me to unsderstand why the methods give so different results? Thanks.

HY

#####################################Connolly surface with r=0 (van de Waals surface)

my \\\$field = \\\$tempDoc->CalculateConnollyField;
my \\\$isosurface = \\\$field->CreateIsosurface([IsoValue => 0,
                                            HasFlippedNormals => "YES", IsoSurfaceKind => "normal"]);

my \\\$freeVolume = \\\$isosurface->EnclosedVolume;

\\\$study->Cell(\\\$rowCounter, 9) = \\\$freeVolume;

my \\\$isosurface = \\\$field->CreateIsosurface([IsoValue => 0,
                                            HasFlippedNormals => "No", IsoSurfaceKind => "normal"]);

my \\\$OccupiedVolume = \\\$isosurface->EnclosedVolume;

\\\$study->Cell(\\\$rowCounter, 10) = \\\$OccupiedVolume;
my \\\$FreeVPercentage=\\\$freeVolume/(\\\$freeVolume+\\\$OccupiedVolume)*100;
\\\$study->Cell(\\\$rowCounter, 11) =\\\$FreeVPercentage ;