NEP vs DFT results

This example show how to calculate energy, forces and stress of structures and compare them with DFT results

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NEP 3 calculator with 1 symbols: C
------------------------------
  zbl                 : False
  radial_cutoff       : 4.2
  angular_cutoff      : 3.7
  n_max_radial        : 10
  n_max_angular       : 8
  basis_size_radial   : 10
  basis_size_angular  : 8
  l_max_3body         : 4
  num_node            : 65
  num_para            : 6903
  element_list        : ['C']
------------------------------


<Figure size 640x480 with 1 Axes>

from pynep.calculate import NEP
from ase.io import read
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.ticker as ticker


def plot_e(ed, er):
    fig = plt.figure()
    # plt.xticks(fontname="Arial", weight='bold')
    plt.title("NEP energy vs DFT energy", fontsize=16)
    ed = ed - np.mean(ed)
    er = er - np.mean(er)
    ax = plt.gca()
    ax.set_aspect(1)
    xmajorLocator = ticker.MaxNLocator(5)
    ymajorLocator = ticker.MaxNLocator(5)
    ax.xaxis.set_major_locator(xmajorLocator)
    ax.yaxis.set_major_locator(ymajorLocator)

    ymajorFormatter = ticker.FormatStrFormatter('%.1f')
    xmajorFormatter = ticker.FormatStrFormatter('%.1f')
    ax.xaxis.set_major_formatter(xmajorFormatter)
    ax.yaxis.set_major_formatter(ymajorFormatter)

    ax.set_xlabel('DFT energy (eV/atom)', fontsize=14)
    ax.set_ylabel('NEP energy (eV/atom)', fontsize=14)

    ax.spines['bottom'].set_linewidth(3)
    ax.spines['left'].set_linewidth(3)
    ax.spines['right'].set_linewidth(3)
    ax.spines['top'].set_linewidth(3)
    ax.tick_params(labelsize=16)


    plt.plot([np.min(ed), np.max(ed)], [np.min(er), np.max(er)],
            color='black',linewidth=3,linestyle='--',)
    plt.scatter(ed, er, zorder=200)

    m1 = min(np.min(ed), np.min(er))
    m2 = max(np.max(ed), np.max(er))
    ax.set_xlim(m1, m2)
    ax.set_ylim(m1, m2)

    rmse = np.sqrt(np.mean((ed-er)**2))
    plt.text(np.min(ed) * 0.85 + np.max(ed) * 0.15,
             np.min(er) * 0.15 + np.max(ed) * 0.85,
             "RMSE: {:.3f} eV/atom".format(rmse), fontsize=14)
    plt.savefig('e.png')
    return fig


def plot_f(fd, fr):
    fig = plt.figure()
    ax = plt.gca()
    plt.title("NEP forces vs DFT forces", fontsize=16)
    ax.set_aspect(1)
    xmajorLocator = ticker.MaxNLocator(5)
    ymajorLocator = ticker.MaxNLocator(5)
    ax.xaxis.set_major_locator(xmajorLocator)
    ax.yaxis.set_major_locator(ymajorLocator)

    ymajorFormatter = ticker.FormatStrFormatter('%.1f')
    xmajorFormatter = ticker.FormatStrFormatter('%.1f')
    ax.xaxis.set_major_formatter(xmajorFormatter)
    ax.yaxis.set_major_formatter(ymajorFormatter)

    ax.set_xlabel('DFT forces (eV/A)', fontsize=14)
    ax.set_ylabel('NEP forces (eV/A)', fontsize=14)

    ax.spines['bottom'].set_linewidth(2)
    ax.spines['left'].set_linewidth(2)
    ax.spines['right'].set_linewidth(2)
    ax.spines['top'].set_linewidth(2)

    ax.tick_params(labelsize=14)

    ax.set_xlim(np.min(fd), np.max(fd))
    ax.set_ylim(np.min(fr), np.max(fr))

    plt.plot([np.min(fd), np.max(fd)], [np.min(fr), np.max(fr)],
            color='black',linewidth=2,linestyle='--')
    plt.scatter(fd.reshape(-1), fr.reshape(-1), s=2)

    m1 = min(np.min(fd), np.min(fr))
    m2 = max(np.max(fd), np.max(fr))
    ax.set_xlim(m1, m2)
    ax.set_ylim(m1, m2)

    rmse = np.sqrt(np.mean((fd-fr)**2))
    plt.text(np.min(fd) * 0.85 + np.max(fd) * 0.15,
             np.min(fr) * 0.15 + np.max(fr) * 0.85,
             "RMSE: {:.3f} eV/A".format(rmse), fontsize=14)
    plt.savefig('f.png')
    return fig

a = read('data.traj', ':')
calc = NEP("C_2022_NEP3.txt")
print(calc)
e1, e2, f1, f2 = [], [], [], []
for i in a:
    i.set_calculator(calc)
    e1.append(i.get_potential_energy() / len(i))
    e2.append(i.info['energy'] / len(i))
    f1.append(i.get_forces().reshape(-1))
    f2.append(i.info['forces'].reshape(-1))
e1 = np.array(e1)
e2 = np.array(e2)
f1 = np.concatenate(f1)
f2 = np.concatenate(f2)
plot_e(e2, e1)
plot_f(f2, f1)