public ChemicalFormulaModification ToHeavyModification(bool c, bool n)
{
var formula = new ChemicalFormula();
if (c)
{
Element carbon = PeriodicTable.GetElement("C");
int carbon12 = ChemicalFormula.Count(carbon[12]);
formula.Add(carbon[12], -carbon12);
formula.Add(carbon[13], carbon12);
}
if (n)
{
Element nitrogen = PeriodicTable.GetElement("N");
int nitrogen14 = ChemicalFormula.Count(nitrogen[14]);
formula.Add(nitrogen[14], -nitrogen14);
formula.Add(nitrogen[15], nitrogen14);
}
return new ChemicalFormulaModification(formula, "#", Site);
}