1# 2# CheMPS2: a spin-adapted implementation of DMRG for ab initio quantum chemistry 3# Copyright (C) 2013-2018 Sebastian Wouters 4# 5# This program is free software; you can redistribute it and/or modify 6# it under the terms of the GNU General Public License as published by 7# the Free Software Foundation; either version 2 of the License, or 8# (at your option) any later version. 9# 10# This program is distributed in the hope that it will be useful, 11# but WITHOUT ANY WARRANTY; without even the implied warranty of 12# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13# GNU General Public License for more details. 14# 15# You should have received a copy of the GNU General Public License along 16# with this program; if not, write to the Free Software Foundation, Inc., 17# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 18# 19 20import numpy as np 21import sys 22import PyCheMPS2 23import ctypes 24 25# Set the seed of the random number generator and cout.precision 26Initializer = PyCheMPS2.PyInitialize() 27Initializer.Init() 28 29# Read in the FCIDUMP 30psi4group = 5 # c2v: see chemps2/Irreps.h 31filename = b'../../tests/matrixelements/CH4.STO3G.FCIDUMP' 32orbirreps = np.array([-1, -1], dtype=ctypes.c_int) # CheMPS2 reads it in from FCIDUMP 33Ham = PyCheMPS2.PyHamiltonian( -1, psi4group, orbirreps, filename ) 34 35# Define the symmetry sector 36TwoS = 0 # Two times the targeted spin 37Nelec = 10 # The number of electrons 38Irrep = 0 # The targeted irrep 39 40# Setting up the Problem 41Prob = PyCheMPS2.PyProblem(Ham, TwoS, Nelec, Irrep) 42 43# Setting up the ConvergenceScheme 44# setInstruction(instruction, D, Econst, maxSweeps, noisePrefactor) 45OptScheme = PyCheMPS2.PyConvergenceScheme(2) # 2 instructions 46OptScheme.setInstruction(0, 30, 1e-10, 3, 0.1) 47OptScheme.setInstruction(1, 1000, 1e-10, 10, 0.0) 48 49# Do DMRG calculation 50theDMRG = PyCheMPS2.PyDMRG(Prob, OptScheme) 51EnergyDMRG = theDMRG.Solve() 52do_3rdm = True 53theDMRG.calc_rdms_and_correlations( do_3rdm ) 54 55# Get a diagonal part of the 4-RDM from DMRG 56L = Ham.getL() 57ham_orbz = 2 58dmrg_diag_4rdm = np.zeros([ L**6 ], dtype=ctypes.c_double) 59theDMRG.Symm4RDM( dmrg_diag_4rdm, ham_orbz, ham_orbz, True ) 60 61# Do FCI calculation 62Nel_up = ( Nelec + TwoS ) / 2 63Nel_down = ( Nelec - TwoS ) / 2 64maxMemWorkMB = 10.0 65FCIverbose = 1 66theFCI = PyCheMPS2.PyFCI(Ham, Nel_up, Nel_down, Irrep, maxMemWorkMB, FCIverbose) 67GSvector = np.zeros([ theFCI.getVecLength() ], dtype=ctypes.c_double) 68GSvector[ theFCI.LowestEnergyDeterminant() ] = 1.0 69EnergyFCI = theFCI.GSDavidson(GSvector) 70theFCI.CalcSpinSquared(GSvector) 71TwoRDM = np.zeros([ L**4 ], dtype=ctypes.c_double) 72theFCI.Fill2RDM(GSvector, TwoRDM) 73RMSerror2DM = 0.0 74for i in range(L): 75 for j in range(L): 76 for k in range(L): 77 for l in range(L): 78 temp = TwoRDM[i + L*(j + L*(k + L*l))] - theDMRG.get2DMA(i,j,k,l) 79 RMSerror2DM += temp*temp 80ThreeRDM = np.zeros([ L**6 ], dtype=ctypes.c_double) 81theFCI.Fill3RDM(GSvector, ThreeRDM) 82RMSerror3DM = 0.0 83for i in range(L): 84 for j in range(L): 85 for k in range(L): 86 for l in range(L): 87 for m in range(L): 88 for n in range(L): 89 temp = ThreeRDM[i + L*(j + L*(k + L*(l + L*(m + L*n))))] - theDMRG.get3DM(i,j,k,l,m,n) 90 RMSerror3DM += temp*temp 91fci_diag_4rdm = np.zeros([ L**6 ], dtype=ctypes.c_double) 92theFCI.Diag4RDM( GSvector, ThreeRDM, ham_orbz, fci_diag_4rdm ) 93RMSerror4DM = np.linalg.norm( 0.5 * dmrg_diag_4rdm - fci_diag_4rdm ) 94RMSerror2DM = np.sqrt(RMSerror2DM) 95RMSerror3DM = np.sqrt(RMSerror3DM) 96print("Frobenius norm of the difference of the DMRG and FCI 2-RDM =", RMSerror2DM) 97print("Frobenius norm of the difference of the DMRG and FCI 3-RDM =", RMSerror3DM) 98print("Frobenius norm of the difference of the DMRG and FCI diag(4-RDM) for fixed orbital", ham_orbz, "=", RMSerror4DM) 99del theFCI 100 101OptScheme.setInstruction(0, 1500, 1e-10, 3, 0.0) 102OptScheme.setInstruction(1, 2000, 1e-10, 10, 0.0) 103EnergyDMRG = theDMRG.Solve() 104theDMRG.calc2DMandCorrelations() 105 106# Clean-up 107# theDMRG.deleteStoredMPS() 108theDMRG.deleteStoredOperators() 109del theDMRG 110del OptScheme 111del Prob 112del Ham 113del Initializer 114 115# Check whether the test succeeded 116if ((np.fabs(EnergyDMRG - EnergyFCI) < 1e-8) and (RMSerror2DM < 1e-3) and (RMSerror3DM < 1e-3) and (RMSerror4DM < 1e-3)): 117 print("================> Did test 10 succeed : yes") 118else: 119 print("================> Did test 10 succeed : no") 120 121