Geant4-DNA behavior within a material with water and metal

Geant4 Version: 11.4.0
Operating System: Ubuntu 24.04.3 LTS
Compiler/Version: gcc 13.3.0
CMake Version: 3.28.3


Dear Geant4 users,

I wish to understand, chemically and physically speaking, what happens when I launch a simulation with a new material that contains a certain percentage of water but also, among others, bismuth and gadolinium.

I have the following warning message :

*** G4Exception : MATERIAL_NOT_DEFINE_USING_ATOM_COUNT
issued by : G4DNAMolecularMaterial::GetDensityTableFor
The material AGuIX_withWater is not defined as a molecular material.
Meaning: The elements should be added to the material using atom count rather than mass fraction (cf. G4Material)
If you want to use DNA processes on liquid water, you should better use the NistManager to create the water material.
Since this message is displayed, it means that the DNA models will not be called.Please note that this message will only appear once even if you are using other methods of G4DNAMolecularMaterial.

*** This is just a warning message. ***

I would like to understand properly what happens in the volume with this material. If the DNA models are not called, why do I see some ROS produced in it ? See below an excerpt from my output files.

MoleculeID Name X_um Y_um Z_um Time_ns Volume
-59 e_aq 6.41525 -0.688161 1.70624 0.001 NanoCluster
-58 e_aq 6.42577 -0.651714 1.69121 0.001 NanoCluster
-111 H 6.4044 -0.68552 1.71747 0.001 Vesicle
-109 H 6.40111 -0.691096 1.71674 0.001 Vesicle
-107 H 6.42789 -0.657131 1.68587 0.001 NanoCluster
-101 H3O 6.41389 -0.668991 1.68397 0.001 NanoCluster

Here is the material I defined :

#include "Materials.hh"
#include "G4Element.hh"
#include "G4NistManager.hh"
#include "G4SystemOfUnits.hh"
using namespace CLHEP;

G4Material* Materials::CreateAGuIX()
{
    // Création des éléments
    G4Element* elBismuth    = new G4Element("Bismuth",   "Bi", 83, 208.98*g/mole);
    G4Element* elGadolinium = new G4Element("Gadolinium","Gd", 64, 157.25*g/mole);
    G4Element* elSilicon    = new G4Element("Silicon",   "Si", 14, 28.09*g/mole);
    G4Element* elCarbon     = new G4Element("Carbon",    "C",  6, 12.01*g/mole);
    G4Element* elNitrogen   = new G4Element("Nitrogen",  "N",  7, 14.01*g/mole);
    G4Element* elOxygen     = new G4Element("Oxygen",    "O",  8, 16.00*g/mole);
    G4Element* elHydrogen   = new G4Element("Hydrogen",  "H",  1, 1.008*g/mole);

    G4double fractionWater = 0.10; // 10% en masse
    G4double density = 1.45*g/cm3;

    // Fractions initiales
    G4double fBi = 0.091;
    G4double fGd = 0.049;
    G4double fSi = 0.10;
    G4double fC  = 0.25;
    G4double fN  = 0.08;
    G4double fO  = 0.23;
    G4double fH  = 0.20;

    // Normalisation pour exclure la fraction d'eau
    G4double remaining = 1.0 - fractionWater;
    fBi *= remaining;
    fGd *= remaining;
    fSi *= remaining;
    fC  *= remaining;
    fN  *= remaining;
    fO  *= remaining;
    fH  *= remaining;

    // Création du matériau
    G4Material* AGuIX = new G4Material("AGuIX_withWater", density, 8);
    AGuIX->AddElement(elBismuth,    fBi);
    AGuIX->AddElement(elGadolinium, fGd);
    AGuIX->AddElement(elSilicon,    fSi);
    AGuIX->AddElement(elCarbon,     fC);
    AGuIX->AddElement(elNitrogen,   fN);
    AGuIX->AddElement(elOxygen,     fO);
    AGuIX->AddElement(elHydrogen,   fH);

    // Ajout de l'eau
    G4Material* water = G4NistManager::Instance()->FindOrBuildMaterial("G4_WATER");
    AGuIX->AddMaterial(water, fractionWater);


    return AGuIX;
}

Thank you in advance for your help,

Regards,

Sarah

Dear,

I guess DNA physics work in your simulation in a physics combination. These physical models can create the chemical species. But these can diffuse only in water. As warning message, chemistry works only in water material