/// <summary>
/// Sample implementation of end-to-end electronic structure problem simulation.
/// </summary>
/// <param name="filename"></param>
public static void SampleWorkflow(
string filename,
string wavefunctionLabel,
IndexConvention indexConvention
)
{
// Deserialize Broombridge from file.
Data broombridge = Deserializers.DeserializeBroombridge(filename);
// A single file can contain multiple problem descriptions. Let us pick the first one.
var problemData = broombridge.ProblemDescriptions.First();
#region Create electronic structure Hamiltonian
// Electronic structure Hamiltonians are usually represented compactly by orbital integrals. Let us construct
// such a Hamiltonian from broombridge.
OrbitalIntegralHamiltonian orbitalIntegralHamiltonian = problemData.OrbitalIntegralHamiltonian;
// We can obtain the full fermion Hamiltonian from the more compact orbital integral representation.
// This transformation requires us to pick a convention for converting a spin-orbital index to a single integer.
// Let us pick one according to the formula `integer = 2 * orbitalIndex + spinIndex`.
FermionHamiltonian fermionHamiltonian = orbitalIntegralHamiltonian.ToFermionHamiltonian(indexConvention);
// We target a qubit quantum computer, which requires a Pauli representation of the fermion Hamiltonian.
// A number of mappings from fermions to qubits are possible. Let us choose the Jordan–Wigner encoding.
PauliHamiltonian pauliHamiltonian = fermionHamiltonian.ToPauliHamiltonian(QubitEncoding.JordanWigner);
#endregion
#region Create wavefunction Ansatzes
// A list of trial wavefunctions can be provided in the Broombridge file. For instance, the wavefunction
// may be a single-reference Hartree--Fock state, a multi-reference state, or a unitary coupled-cluster state.
// In this case, Broombridge indexes the fermion operators with spin-orbitals instead of integers.
Dictionary <string, FermionWavefunction <SpinOrbital> > inputStates = problemData.Wavefunctions ?? new Dictionary <string, FermionWavefunction <SpinOrbital> >();
// If no states are provided, use the Hartree--Fock state.
// As fermion operators the fermion Hamiltonian are already indexed by, we now apply the desired
// spin-orbital -> integer indexing convention.
FermionWavefunction <int> inputState = inputStates.ContainsKey(wavefunctionLabel)
? inputStates[wavefunctionLabel].ToIndexing(indexConvention)
: fermionHamiltonian.CreateHartreeFockState(problemData.NElectrons);
#endregion
#region Pipe to QSharp and simulate
// We now convert this Hamiltonian and a selected state to a format that than be passed onto the QSharp component
// of the library that implements quantum simulation algorithms.
var qSharpHamiltonian = pauliHamiltonian.ToQSharpFormat();
var qSharpWavefunction = inputState.ToQSharpFormat();
var qSharpData = QSharpFormat.Convert.ToQSharpFormat(qSharpHamiltonian, qSharpWavefunction);
#endregion
}
/// <summary>
/// Loads a Hamiltonian from integral data represented
/// in LIQ𝑈𝑖|⟩ format.
/// Please see the <a href="https://stationq.github.io/Liquid/docs/LIQUiD.pdf">
/// LIQ𝑈𝑖|⟩ documentation</a> for further details about the
/// format parsed by this method.
/// </summary>
/// <param name="lines">Sequence of text describing terms of Hamiltonian.</param>
/// <returns>
/// An instance of <see cref="FermionHamiltonian"/> representing the
/// data contained in <paramref name="lines"/>.
/// </returns>
public static FermionHamiltonian LoadFromLiquid(string line)
{
var regexMiscellaneous = new Regex(@"((info=(?<info>[^\s]*)))");
var regexnuc = new Regex(@"nuc=(?<nuc>-?\s*\d*.\d*)");
var regexPQ = new Regex(@"(^|\s+)(?<p>\d+),(?<q>\d+)\D*=\s*(?<coeff>-?\s*\d*.\d*)e?(?<exponent>-?\d*)");
var regexPQRS = new Regex(@"(^|\s+)(?<p>\d+)\D+(?<q>\d+)\D+(?<r>\d+)\D+(?<s>\d+)\D*=\s*(?<coeff>-?\s*\d*.\d*)e?(?<exponent>-?\d*)");
Double coulombRepulsion = 0.0;
var fileHIJTerms = new Dictionary <Int64[], Double>(new Extensions.IntArrayIEqualityComparer());
var fileHIJKLTerms = new Dictionary <Int64[], Double>(new Extensions.IntArrayIEqualityComparer());
var hamiltonian = new FermionHamiltonian();
var nOrbitals = 0L;
Match stringMisc = regexMiscellaneous.Match(line);
if (stringMisc.Success)
{
hamiltonian.MiscellaneousInformation = stringMisc.Groups["info"].ToString();
}
Match stringnuc = regexnuc.Match(line);
if (stringnuc.Success)
{
hamiltonian.EnergyOffset = Double.Parse(stringnuc.Groups["nuc"].ToString());
}
foreach (Match stringPQ in regexPQ.Matches(line))
{
if (stringPQ.Success)
{
var p = Int64.Parse(stringPQ.Groups["p"].ToString());
var q = Int64.Parse(stringPQ.Groups["q"].ToString());
var coeff = Double.Parse(stringPQ.Groups["coeff"].ToString());
var exponentString = stringPQ.Groups["exponent"].ToString();
var exponent = 0.0;
if (exponentString != "")
{
exponent = Double.Parse(stringPQ.Groups["exponent"].ToString());
}
nOrbitals = new long[] { nOrbitals, p + 1, q + 1 }.Max();
var orbitalIntegral = new OrbitalIntegral(new Int64[] { p, q }, coeff * (10.0).Pow(exponent));
var orbitalIntegralCanonical = orbitalIntegral.ToCanonicalForm();
//Logger.Message.WriteLine($"1e orbital { orbitalIntegral.Print()}, { orbitalIntegralCanonical.Print()}");
if (fileHIJTerms.ContainsKey(orbitalIntegralCanonical.OrbitalIndices))
{
// Check consistency
if (fileHIJTerms[orbitalIntegralCanonical.OrbitalIndices] != orbitalIntegral.Coefficient)
{
// Consistency check failed.
throw new System.NotSupportedException(
$"fileHPQTerm Consistency check fail. " +
$"Orbital integral {orbitalIntegral} coefficient {orbitalIntegral.Coefficient}" +
$"does not match recorded {orbitalIntegralCanonical} coefficient {fileHIJTerms[orbitalIntegral.OrbitalIndices]}.");
}
else
{
// Consistency check passed.
}
//Logger.Message.WriteLine($"1e orbital collision { orbitalIntegral.Print()}, { orbitalIntegralCanonical.Print()}");
}
else
{
fileHIJTerms.Add(orbitalIntegralCanonical.OrbitalIndices, orbitalIntegralCanonical.Coefficient);
}
}
}
foreach (Match stringPQRS in regexPQRS.Matches(line))
{
if (stringPQRS.Success)
{
var p = Int64.Parse(stringPQRS.Groups["p"].ToString());
var q = Int64.Parse(stringPQRS.Groups["q"].ToString());
var r = Int64.Parse(stringPQRS.Groups["r"].ToString());
var s = Int64.Parse(stringPQRS.Groups["s"].ToString());
var coeff = Double.Parse(stringPQRS.Groups["coeff"].ToString());
var exponentString = stringPQRS.Groups["exponent"].ToString();
var exponent = 0.0;
if (exponentString != "")
{
exponent = Double.Parse(stringPQRS.Groups["exponent"].ToString());
}
nOrbitals = new long[] { nOrbitals, p + 1, q + 1, r + 1, s + 1 }.Max();
var orbitalIntegral = new OrbitalIntegral(new Int64[] { p, q, r, s }, coeff * (10.0).Pow(exponent));
var orbitalIntegralCanonical = orbitalIntegral.ToCanonicalForm();
//Logger.Message.WriteLine($"2e orbital: { orbitalIntegral.Print()}, { orbitalIntegralCanonical.Print()}");
if (fileHIJKLTerms.ContainsKey(orbitalIntegralCanonical.OrbitalIndices))
{
// Check consistency
if (fileHIJKLTerms[orbitalIntegralCanonical.OrbitalIndices] != orbitalIntegral.Coefficient)
{
// Consistency check failed.
throw new System.NotSupportedException(
$"fileHPQRSTerm Consistency check fail. " +
$"Orbital integral {orbitalIntegral.OrbitalIndices} coefficient {orbitalIntegral.Coefficient}" +
$"does not match recorded {orbitalIntegralCanonical.OrbitalIndices} coefficient {fileHIJKLTerms[orbitalIntegral.OrbitalIndices]}.");
}
else
{
// Consistency check passed.
}
//Logger.Message.WriteLine($"2e orbital collision { orbitalIntegral.Print()}, { orbitalIntegralCanonical.Print()}");
}
else
{
fileHIJKLTerms.Add(orbitalIntegralCanonical.OrbitalIndices, orbitalIntegralCanonical.Coefficient);
}
}
}
hamiltonian.NOrbitals = nOrbitals;
foreach (var ijTerm in fileHIJTerms)
{
hamiltonian.AddFermionTerm(new OrbitalIntegral(ijTerm.Key, ijTerm.Value));
}
foreach (var ijklTerm in fileHIJKLTerms)
{
hamiltonian.AddFermionTerm(new OrbitalIntegral(ijklTerm.Key, ijklTerm.Value));
}
hamiltonian.SortAndAccumulate();
return(hamiltonian);
}