private void CalcOffSiteInteraction(TightBinding tb, Matrix _S, Matrix _C, InteractionPair interaction, double structureFactor)
{
foreach (int l1 in interaction.OrbitalsLeft)
{
foreach (int l2 in interaction.OrbitalsLeft)
{
foreach (int l3 in interaction.OrbitalsRight)
{
foreach (int l4 in interaction.OrbitalsRight)
{
int i = GetIndex(tb, l1, l2);
int j = GetIndex(tb, l3, l4);
double Sval = 0, Cval = 0;
if (l1 == l2 && l2 == l3 && l3 == l4)
{
Sval = -0.5 * interaction.Exchange * structureFactor;
Cval = (2 * interaction.InterorbitalU - 0.5 * interaction.Exchange) * structureFactor;
}
else if (l1 == l2 && l2 != l3 && l3 == l4)
{
Sval = -0.25 * interaction.Exchange * structureFactor;
Cval = (2 * interaction.InterorbitalU - 0.5 * interaction.Exchange) * structureFactor;
}
_S[i, j] += Sval;
_S[j, i] += Sval;
_C[i, j] += Cval;
_C[j, i] += Cval;
}
}
}
}
}
private void CalcOnSiteInteraction(TightBinding tb, Matrix _S, Matrix _C, InteractionPair interaction)
{
foreach (int l1 in interaction.OrbitalsLeft)
{
foreach (int l2 in interaction.OrbitalsLeft)
{
foreach (int l3 in interaction.OrbitalsRight)
{
foreach (int l4 in interaction.OrbitalsRight)
{
int i = GetIndex(tb, l1, l2);
int j = GetIndex(tb, l3, l4);
if (l1 == l2 && l2 == l3 && l3 == l4)
{
_S[i, j] += interaction.HubbardU;
_C[i, j] += interaction.HubbardU;
}
else if (l1 == l4 && l4 != l2 && l2 == l3)
{
_S[i, j] += interaction.InterorbitalU;
_C[i, j] += (-interaction.InterorbitalU + interaction.Exchange);
}
else if (l1 == l2 && l2 != l3 && l3 == l4)
{
_S[i, j] += interaction.Exchange;
_C[i, j] += 2 * interaction.InterorbitalU - interaction.Exchange;
}
else if (l1 == l3 && l3 != l2 && l2 == l4)
{
_S[i, j] += interaction.PairHopping;
_C[i, j] += interaction.PairHopping;
}
}
}
}
}
}
private void ReadInteractionSection()
{
if (tb.Interactions != null)
ThrowEx("Multiple Interaction sections found.");
tb.Interactions = new InteractionList();
if (LineType != LineType.NewSubSection && LineType != LineType.NewSection)
{
if (Line.ToLowerInvariant().StartsWith( "adjust"))
{
tb.Interactions.AdjustInteractions = true;
string ltext = Line.ToLowerInvariant().Substring(6);
double val;
if (double.TryParse(ltext, out val) == false)
{
val = 0.001;
}
if (val <= 0 || val >= 1)
{
ThrowEx("Interaction adjustment should be between 0 and 1.");
}
tb.Interactions.MaxEigenvalue = 1 - val;
}
ReadNextLine();
}
while (!EOF && LineType != LineType.NewSection)
{
if (LineType != LineType.NewSubSection)
ThrowEx("Could not understand contents of interaction section.");
string[] values = ReadSubSectionParameters();
InteractionPair inter = new InteractionPair(tb.sites, values[0], values[1]);
if (inter.OrbitalsLeft.Count == 0) ThrowEx("Could not identify interaction group \"" + values[0] + "\".");
if (inter.OrbitalsRight.Count == 0) ThrowEx("Could not identify interaction group \"" + values[1] + "\".");
ReadNextLine();
string[] interactionVals = Line.Split(new char[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
double[] vals = interactionVals.Select(x => double.Parse(x)).ToArray();
ReadNextLine();
while (!EOF && LineType != LineType.NewSection && LineType != LineType.NewSubSection)
{
Vector3 vec = Vector3.Parse(Line);
inter.Vectors.Add(vec);
ReadNextLine();
}
Orbital left = tb.Orbitals[inter.OrbitalsLeft[0]];
Orbital right = tb.Orbitals[inter.OrbitalsRight[0]];
Vector3 delta = left.Location - right.Location;
if (delta.Magnitude > 1e-8 && inter.Vectors.Count == 0)
{
ThrowEx(string.Format(
"Interaction is specified between groups {0} and {1}, but they are at different locations and no vectors were given!",
values[0], values[1]));
}
if (inter.OnSite)
{
if (interactionVals.Length > 4)
ThrowEx("Found too many parameters in the interaction.");
inter.HubbardU = double.Parse(interactionVals[0]);
if (interactionVals.Length > 1) inter.InterorbitalU = double.Parse(interactionVals[1]);
if (interactionVals.Length > 2) inter.Exchange = double.Parse(interactionVals[2]);
if (interactionVals.Length > 3) inter.PairHopping = double.Parse(interactionVals[3]);
}
else
{
if (interactionVals.Length > 2)
ThrowEx("Found too many parameters in the interaction. Only two (Hubbard and exchange) allowed for intersite interaction");
inter.InterorbitalU = double.Parse(interactionVals[0]);
inter.Exchange = double.Parse(interactionVals[1]);
}
tb.Interactions.Add(inter);
}
}
