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- //////////////////////////////////////////////////////////////////////////////////////////
- // Author: Manish Agarwal and Gourav Shrivastava , IIT Delhi
- //////////////////////////////////////////////////////////////////////////////////////////
- // Copyright (c) 2021 NVIDIA Corporation. All rights reserved.
- #include <stdio.h>
- #include <stdlib.h>
- #include <iostream>
- #include <fstream>
- #include <cmath>
- #include <cstring>
- #include <cstdio>
- #include <iomanip>
- #include "dcdread.h"
- #include <assert.h>
- #include <nvtx3/nvToolsExt.h>
- //Function declation where distances are calculated
- void pair_gpu(const double *d_x, const double *d_y, const double *d_z,
- unsigned long long int *d_g2, int numatm, int nconf,
- const double xbox, const double ybox, const double zbox,
- int d_bin);
- int main(int argc, char *argv[])
- {
- double xbox, ybox, zbox;
- double *h_x, *h_y, *h_z;
- unsigned long long int *h_g2;
- int nbin;
- int numatm, nconf, inconf;
- string file;
- /////////////////Input Details//////////////////////////////////////////////
- inconf = 10;
- nbin = 2000;
- file = "../input/alk.traj.dcd";
- ///////////////////////////////////////
- std::ifstream infile;
- infile.open(file.c_str());
- if (!infile)
- {
- cout << "file " << file.c_str() << " not found\n";
- return 1;
- }
- assert(infile);
- ofstream pairfile, stwo;
- //Output file storing the RDF values
- pairfile.open("RDF.dat");
- //Output file storing the entropy. This value will be used to check the correctness of output
- stwo.open("Pair_entropy.dat");
- /////////////////////////////////////////////////////////
- dcdreadhead(&numatm, &nconf, infile);
- cout << "Dcd file has " << numatm << " atoms and " << nconf << " frames" << endl;
- if (inconf > nconf)
- cout << "nconf is reset to " << nconf << endl;
- else
- {
- nconf = inconf;
- }
- cout << "Calculating RDF for " << nconf << " frames" << endl;
- ////////////////////////////////////////////////////////
- unsigned long long int sizef = nconf * numatm * sizeof(double);
- unsigned long long int sizebin = nbin * sizeof(unsigned long long int);
- h_x = (double *)malloc(sizef);
- h_y = (double *)malloc(sizef);
- h_z = (double *)malloc(sizef);
- h_g2 = (unsigned long long int *)malloc(sizebin);
- memset(h_g2, 0, sizebin);
- /////////reading cordinates//////////////////////////////////////////////
- nvtxRangePush("Read_File");
- double ax[numatm], ay[numatm], az[numatm];
- for (int i = 0; i < nconf; i++)
- {
- dcdreadframe(ax, ay, az, infile, numatm, xbox, ybox, zbox);
- for (int j = 0; j < numatm; j++)
- {
- h_x[i * numatm + j] = ax[j];
- h_y[i * numatm + j] = ay[j];
- h_z[i * numatm + j] = az[j];
- }
- }
- nvtxRangePop(); //pop for REading file
- cout << "Reading of input file is completed" << endl;
- /////////////////////This is where we will concentrate//////////////////
- nvtxRangePush("Pair_Calculation");
- pair_gpu(h_x, h_y, h_z, h_g2, numatm, nconf, xbox, ybox, zbox, nbin);
- nvtxRangePop(); //Pop for Pair Calculation
- ////////////////////////////////////////////////////////////////////////
- double pi = acos(-1.0l);
- double rho = (numatm) / (xbox * ybox * zbox);
- double norm = (4.0l * pi * rho) / 3.0l;
- double rl, ru, nideal;
- double g2[nbin];
- double r, gr, lngr, lngrbond, s2 = 0.0l, s2bond = 0.0l;
- double box = min(xbox, ybox);
- box = min(box, zbox);
- double del = box / (2.0l * nbin);
- // Loop to calculate entropy
- nvtxRangePush("Entropy_Calculation");
- for (int i = 0; i < nbin; i++)
- {
- rl = (i)*del;
- ru = rl + del;
- nideal = norm * (ru * ru * ru - rl * rl * rl);
- g2[i] = (double)h_g2[i] / ((double)nconf * (double)numatm * nideal);
- r = (i)*del;
- pairfile << (i + 0.5l) * del << " " << g2[i] << endl;
- if (r < 2.0l)
- {
- gr = 0.0l;
- }
- else
- {
- gr = g2[i];
- }
- if (gr < 1e-5)
- {
- lngr = 0.0l;
- }
- else
- {
- lngr = log(gr);
- }
- if (g2[i] < 1e-6)
- {
- lngrbond = 0.0l;
- }
- else
- {
- lngrbond = log(g2[i]);
- }
- s2 = s2 - 2.0l * pi * rho * ((gr * lngr) - gr + 1.0l) * del * r * r;
- s2bond = s2bond - 2.0l * pi * rho * ((g2[i] * lngrbond) - g2[i] + 1.0l) * del * r * r;
- }
- nvtxRangePop(); //Pop for Entropy Calculation
- stwo << "s2 value is " << s2 << endl;
- stwo << "s2bond value is " << s2bond << endl;
- cout << "#Freeing Host memory" << endl;
- free(h_x);
- free(h_y);
- free(h_z);
- free(h_g2);
- cout << "#Number of atoms processed: " << numatm << endl
- << endl;
- cout << "#Number of confs processed: " << nconf << endl
- << endl;
- return 0;
- }
- int round(float num)
- {
- return num < 0 ? num - 0.5 : num + 0.5;
- }
- void pair_gpu(const double *d_x, const double *d_y, const double *d_z,
- unsigned long long int *d_g2, int numatm, int nconf,
- const double xbox, const double ybox, const double zbox, int d_bin)
- {
- double r, cut, dx, dy, dz;
- int ig2;
- double box;
- int myround;
- box = min(xbox, ybox);
- box = min(box, zbox);
- double del = box / (2.0 * d_bin);
- cut = box * 0.5;
- printf("\n %d %d ", nconf, numatm);
- for (int frame = 0; frame < nconf; frame++)
- {
- printf("\n %d ", frame);
- for (int id1 = 0; id1 < numatm; id1++)
- {
- for (int id2 = 0; id2 < numatm; id2++)
- {
- dx = d_x[frame * numatm + id1] - d_x[frame * numatm + id2];
- dy = d_y[frame * numatm + id1] - d_y[frame * numatm + id2];
- dz = d_z[frame * numatm + id1] - d_z[frame * numatm + id2];
- dx = dx - xbox * (round(dx / xbox));
- dy = dy - ybox * (round(dy / ybox));
- dz = dz - zbox * (round(dz / zbox));
- r = sqrtf(dx * dx + dy * dy + dz * dz);
- if (r < cut)
- {
- ig2 = (int)(r / del);
- d_g2[ig2] = d_g2[ig2] + 1;
- }
- }
- }
- }
- }
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