testXCFunctional.C 3.42 KB
 Francois Gygi committed May 20, 2004 1 2 //////////////////////////////////////////////////////////////////////////////// //  Francois Gygi committed Aug 13, 2008 3 4 5 6 // Copyright (c) 2008 The Regents of the University of California // // This file is part of Qbox //  Francois Gygi committed Sep 08, 2008 7 8 // Qbox is distributed under the terms of the GNU General Public License // as published by the Free Software Foundation, either version 2 of  Francois Gygi committed Aug 13, 2008 9 10 11 12 13 14 // the License, or (at your option) any later version. // See the file COPYING in the root directory of this distribution // or . // //////////////////////////////////////////////////////////////////////////////// //  Francois Gygi committed May 20, 2004 15 16 17 18 19 20 // testXCFunctional.C // //////////////////////////////////////////////////////////////////////////////// // Test an XC functional by computing the xc energy of a gaussian // of width 0.1 a.u. in a cube of side 1.0 a.u.  Francois Gygi committed Oct 19, 2007 21 // With a cube of side 1.0 and 32x32x32 points,  Francois Gygi committed May 20, 2004 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 // The LDA xc energy must be -2.8105 a.u. // dExc/da must be 0.911682 #include #include #include "LDAFunctional.h" #include "PBEFunctional.h" #include "Timer.h" #include #include using namespace std; int main(int argc, char **argv) { // use: testxcf alat np if ( argc != 3 ) { cout << " use: testXCFunctional alat np" << endl; return 0; } assert(argc==3); double a = atof(argv[1]); double omega = a*a*a; int n = atoi(argv[2]); int n3 = n*n*n; vector > rh; rh.resize(1); rh[0].resize(n3);  Francois Gygi committed Oct 19, 2007 50   Francois Gygi committed May 20, 2004 51 52 53  XCFunctional *xcf_list[2]; xcf_list[0] = new LDAFunctional(rh); xcf_list[1] = new PBEFunctional(rh);  Francois Gygi committed Oct 19, 2007 54   Francois Gygi committed May 20, 2004 55 56 57 58 59  for ( int ixcf = 0; ixcf < 2; ixcf++ ) { Timer tm; XCFunctional *xcf = xcf_list[ixcf]; cout << endl << " Functional name: " << xcf->name() << endl;  Francois Gygi committed Oct 19, 2007 60   Francois Gygi committed May 20, 2004 61 62 63 64 65 66 67  double *grad_rho[3]; if ( xcf->isGGA() ) { grad_rho[0] = xcf->grad_rho[0]; grad_rho[1] = xcf->grad_rho[1]; grad_rho[2] = xcf->grad_rho[2]; }  Francois Gygi committed Oct 19, 2007 68   Francois Gygi committed May 20, 2004 69 70 71 72 73  const double rc = 0.1 * a; const double rc2 = rc * rc; const double pi = M_PI; const double fac = 1.0 / ( pow(pi,1.5) * rc*rc*rc ); double sum = 0.0;  Francois Gygi committed Oct 19, 2007 74   Francois Gygi committed May 20, 2004 75 76 77 78 79 80 81 82 83 84 85 86 87  for ( int i = 0; i < n; i++ ) { double x = ( i * a ) / n - a/2; for ( int j = 0; j < n; j++ ) { double y = ( j * a ) / n - a/2; for ( int k = 0; k < n; k++ ) { double z = ( k * a ) / n - a/2; double r2 = x*x + y*y + z*z; int ii = i + n * ( j + n * k ); rh[0][ii] = fac * exp( -r2 / rc2 ); sum += rh[0][ii];  Francois Gygi committed Oct 19, 2007 88   Francois Gygi committed May 20, 2004 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104  if ( xcf->isGGA() ) { grad_rho[0][ii] = - rh[0][ii] * 2.0 * x / rc2; grad_rho[1][ii] = - rh[0][ii] * 2.0 * y / rc2; grad_rho[2][ii] = - rh[0][ii] * 2.0 * z / rc2; } } } } sum = sum * omega / n3; // the density should be normalized cout << " Integrated density: " << sum << endl; tm.start(); xcf->setxc(); tm.stop();  Francois Gygi committed Oct 19, 2007 105   Francois Gygi committed May 20, 2004 106 107 108 109  double *exc = xcf->exc; double excsum = 0.0; for ( int i = 0; i < n3; i++ ) excsum += rh[0][i] * exc[i];  Francois Gygi committed Oct 19, 2007 110   Francois Gygi committed May 20, 2004 111 112 113 114 115 116 117 118 119  cout << " Total xc energy: " << excsum * omega / n3 << endl; // if not a GGA, compute dExc/da if ( !xcf->isGGA() ) { double *vxc1 = xcf->vxc1; double dxcsum = 0.0; for ( int i = 0; i < n3; i++ ) dxcsum += rh[0][i] * ( exc[i] - vxc1[i] );  Francois Gygi committed Oct 19, 2007 120   Francois Gygi committed May 20, 2004 121 122 123 124 125 126 127  // Note: the energy variation is 3 * dExc/da * delta(a) cout << " dExc/da: " << dxcsum * omega / ( n3 * a ) << endl; } cout << " " << xcf->name() << " time: " << tm.real() << endl; } // ixcf return 0; }