double SpinAdapted::det_energy (const Slater& s)
{
// energy of a single slater determinant, used in truncation
double energy = 0;
Slater bra;
Slater ket;
for (int i = 0; i < s.size (); ++i)
{
ket = s;
bra = s;
energy += ket.trace (bra.d(i).c(i)) *
v_1 (i,i);
}
// diagonal
for (int i = 0; i < s.size (); ++i)
for (int j = 0; j < s.size (); ++j)
{
ket = s;
bra = s;
energy += .5 * ket.trace (bra.d(j).d(i).c(j).c(i))
* (v_2 (i,j,j,i) - v_2 (i,j,i,j));
}
return energy;
}
bool Slater::operator== (const Slater& b) const
{
if (this->size() != b.size())
{
return 0;
}
for (int i = 0; i < this->size(); ++i)
{
if ((*this)[i] != b[i])
{
return 0;
}
}
return 1;
}
