# OEGet2dPSA¶

Returns the topological polar surface area for a given molecule as described in the Polar Surface Area section. The SandP parameter controls whether sulfur and phosphorus should be counted towards the total surface area. See example in Figure: Example of depicting the atom contributions of the polar surface area.

Warning

TPSA values are mildly sensitive to the protonation state of a molecule.

The atomPSA parameter can be used to retrieve the contribution of each atom to the total polar surface area as shown in Listing 1.

Listing 1: Example of retrieving individual atom contributions to PSA

float[] atomPSA = new float[mol.GetMaxAtomIdx()];
float psa = OEMolProp.OEGet2dPSA(mol, atomPSA);

Console.WriteLine("PSA = " + psa);
foreach (OEAtomBase atom in mol.GetAtoms())
{
uint idx = atom.GetIdx();
Console.WriteLine("{0:d} {1:0.00}", idx, atomPSA[idx]);
}


Example of depicting the atom contributions of the polar surface area (ignoring S and P atoms)

(Darker colors and longer spikes indicate larger PSA atom contributions)

Example of depicting the atom contributions of the polar surface area (considering S and P atoms)

(Darker colors and longer spikes indicate larger PSA atom contributions)