Terachem

arkane/common.py

@@ -41,6 +41,7 @@
 
 import rmgpy.constants as constants
 from rmgpy import __version__
+from rmgpy.exceptions import InputError
 from rmgpy.molecule.element import get_element
 from rmgpy.molecule.translator import to_inchi, to_inchi_key
 from rmgpy.pdep.collision import SingleExponentialDown
@@ -57,6 +58,8 @@
 
 from arkane.pdep import PressureDependenceJob
 
+################################################################################
+
 
 # Add a custom string representer to use block literals for multiline strings
 def str_repr(dumper, data):
@@ -353,9 +356,9 @@ def check_conformer_energy(energies, path):
     energies = np.array(energies, np.float64)
     e_diff = (energies[0] - np.min(energies)) * constants.E_h * constants.Na / 1000
     if e_diff >= 2:  # we choose 2 kJ/mol to be the critical energy
-        logging.warning('the species corresponding to {path} is different in energy from the lowest energy conformer '
-                        'by {diff} kJ/mol. This can cause significant errors in your computed rate constants.'
-                        .format(path=os.path.basename(path), diff=e_diff))
+        logging.warning(f'The species corresponding to {os.path.basename(path)} is different in energy from the '
+                        f'lowest energy conformer by {e_diff:.2f} kJ/mol. This can cause significant errors in '
+                        f'your computed thermodynamic properties and rate coefficients.')
 
 
 def get_element_mass(input_element, isotope=None):
@@ -587,3 +590,94 @@ def get_element_mass(input_element, isotope=None):
     'Lv': [[293, 293.20449]],
     'Ts': [[292, 292.20746]],
     'Og': [[294, 294.21392]]}
+
+
+def get_center_of_mass(coords, numbers=None, symbols=None):
+    """
+    Calculate and return the 3D position of the center of mass of the current geometry.
+    Either ``numbers`` or ``symbols`` must be given.
+
+    Args:
+        coords (np.array): Entries are 3-length lists of xyz coordinates for an atom.
+        numbers (np.array, list): Entries are atomic numbers corresponding to coords.
+        symbols (list): Entries are atom symbols corresponding to coords.
+
+    Returns:
+        np.array: The center of mass coordinates.
+    """
+    if symbols is None and numbers is None:
+        raise IndexError('Either symbols or numbers must be given.')
+    if numbers is not None:
+        symbols = [symbol_by_number[number] for number in numbers]
+    center, total_mass = np.zeros(3, np.float64), 0
+    for coord, symbol in zip(coords, symbols):
+        mass = get_element_mass(symbol)[0]
+        center += mass * coord
+        total_mass += mass
+    center /= total_mass
+    return center
+
+
+def get_moment_of_inertia_tensor(coords, numbers=None, symbols=None):
+    """
+    Calculate and return the moment of inertia tensor for the current
+    geometry in amu*angstrom^2. If the coordinates are not at the center of mass,
+    they are temporarily shifted there for the purposes of this calculation.
+    Adapted from J.W. Allen: https://github.com/jwallen/ChemPy/blob/master/chempy/geometry.py
+
+    Args:
+        coords (np.array): Entries are 3-length lists of xyz coordinates for an atom.
+        numbers (np.array, list): Entries are atomic numbers corresponding to coords.
+        symbols (list): Entries are atom symbols corresponding to coords.
+
+    Returns:
+        np.array: The 3x3 moment of inertia tensor.
+    Raises:
+        InputError: If neither ``symbols`` nor ``numbers`` are given, or if they have a different length than ``coords``
+    """
+    if symbols is None and numbers is None:
+        raise InputError('Either symbols or numbers must be given.')
+    if numbers is not None:
+        symbols = [symbol_by_number[number] for number in numbers]
+    if len(coords) != len(symbols):
+        raise InputError(f'The number of atoms ({len(symbols)}) is not equal to the number of '
+                         f'atomic coordinates ({len(list(coords))})')
+    tensor = np.zeros((3, 3), np.float64)
+    center_of_mass = get_center_of_mass(coords=coords, numbers=numbers, symbols=symbols)
+    for symbol, coord in zip(symbols, coords):
+        mass = get_element_mass(symbol)[0]
+        cm_coord = coord - center_of_mass
+        tensor[0, 0] += mass * (cm_coord[1] * cm_coord[1] + cm_coord[2] * cm_coord[2])
+        tensor[1, 1] += mass * (cm_coord[0] * cm_coord[0] + cm_coord[2] * cm_coord[2])
+        tensor[2, 2] += mass * (cm_coord[0] * cm_coord[0] + cm_coord[1] * cm_coord[1])
+        tensor[0, 1] -= mass * cm_coord[0] * cm_coord[1]
+        tensor[0, 2] -= mass * cm_coord[0] * cm_coord[2]
+        tensor[1, 2] -= mass * cm_coord[1] * cm_coord[2]
+    tensor[1, 0] = tensor[0, 1]
+    tensor[2, 0] = tensor[0, 2]
+    tensor[2, 1] = tensor[1, 2]
+    return tensor
+
+
+def get_principal_moments_of_inertia(coords, numbers=None, symbols=None):
+    """
+    Calculate and return the principal moments of inertia in amu*angstrom^2 in decending order
+    and the corresponding principal axes for the current geometry.
+    The moments of inertia are in translated to the center of mass. The principal axes have unit lengths.
+    Adapted from J.W. Allen: https://github.com/jwallen/ChemPy/blob/master/chempy/geometry.py
+
+    Args:
+        coords (np.array): Entries are 3-length lists of xyz coordinates for an atom.
+        numbers (np.array, list): Entries are atomic numbers corresponding to coords.
+        symbols (list): Entries are atom symbols corresponding to coords.
+
+    Returns:
+        tuple: The principal moments of inertia.
+        tuple: The corresponding principal axes.
+    """
+    tensor0 = get_moment_of_inertia_tensor(coords=coords, numbers=numbers, symbols=symbols)
+    # Since tensor0 is real and symmetric, diagonalization is always possible
+    principal_moments_of_inertia, axes = np.linalg.eig(tensor0)
+    principal_moments_of_inertia, axes = zip(*sorted(zip(np.ndarray.tolist(principal_moments_of_inertia),
+                                                         np.ndarray.tolist(axes)), reverse=True))
+    return principal_moments_of_inertia, axes

arkane/commonTest.py

@@ -46,7 +46,8 @@
 from rmgpy.thermo import NASA, ThermoData
 
 from arkane import Arkane, input
-from arkane.common import ArkaneSpecies, get_element_mass
+from arkane.common import ArkaneSpecies, get_element_mass, get_center_of_mass, \
+    get_moment_of_inertia_tensor, get_principal_moments_of_inertia
 from arkane.input import job_list
 from arkane.statmech import InputError, StatMechJob
 
@@ -443,9 +444,9 @@ def tearDownClass(cls):
                     shutil.rmtree(item_path)
 
 
-class TestGetMass(unittest.TestCase):
+class TestMomentOfInertia(unittest.TestCase):
     """
-    Contains unit tests of common.py
+    Contains unit tests for attaining moments of inertia from the 3D coordinates.
     """
 
     def test_get_mass(self):
@@ -455,8 +456,102 @@ def test_get_mass(self):
         self.assertEquals(get_element_mass('C', 13), (13.00335483507, 6))  # test specific isotope
         self.assertEquals(get_element_mass('Bk'), (247.0703073, 97))  # test a two-element array (no isotope data)
 
+    def test_get_center_of_mass(self):
+        """Test attaining the center of mass"""
+        symbols = ['C', 'H', 'H', 'H', 'H']
+        coords = np.array([[0.0000000, 0.0000000, 0.0000000],
+                           [0.6269510, 0.6269510, 0.6269510],
+                           [-0.6269510, -0.6269510, 0.6269510],
+                           [-0.6269510, 0.6269510, -0.6269510],
+                           [0.6269510, -0.6269510, -0.6269510]], np.float64)
+        center_of_mass = get_center_of_mass(coords=coords, symbols=symbols)
+        for cm_coord in center_of_mass:
+            self.assertEqual(cm_coord, 0.0)
+
+        symbols = ['O', 'C', 'C', 'H', 'H', 'H', 'H', 'H', 'H']
+        coords = np.array([[1.28706525, 0.52121353, 0.04219198],
+                           [0.39745682, -0.35265044, -0.63649234],
+                           [0.36441173, -1.68197093, 0.08682400],
+                           [-0.59818222, 0.10068325, -0.65235399],
+                           [0.74799641, -0.48357798, -1.66461710],
+                           [0.03647269, -1.54932006, 1.12314420],
+                           [-0.31340646, -2.38081353, -0.41122551],
+                           [1.36475837, -2.12581592, 0.12433596],
+                           [2.16336803, 0.09985803, 0.03295192]], np.float64)
+        center_of_mass = get_center_of_mass(coords=coords, symbols=symbols)
+        self.assertAlmostEqual(center_of_mass[0], 0.7201, 3)
+        self.assertAlmostEqual(center_of_mass[1], -0.4880, 3)
+        self.assertAlmostEqual(center_of_mass[2], -0.1603, 3)
+
+        numbers = [6, 6, 8, 1, 1, 1, 1, 1, 1]
+        coords = np.array([[1.1714680, -0.4048940, 0.0000000],
+                           [0.0000000, 0.5602500, 0.0000000],
+                           [-1.1945070, -0.2236470, 0.0000000],
+                           [-1.9428910, 0.3834580, 0.0000000],
+                           [2.1179810, 0.1394450, 0.0000000],
+                           [1.1311780, -1.0413680, 0.8846660],
+                           [1.1311780, -1.0413680, -0.8846660],
+                           [0.0448990, 1.2084390, 0.8852880],
+                           [0.0448990, 1.2084390, -0.8852880]], np.float64)
+        center_of_mass = get_center_of_mass(coords=coords, numbers=numbers)
+        self.assertAlmostEqual(center_of_mass[0], -0.0540, 3)
+        self.assertAlmostEqual(center_of_mass[1], -0.0184, 3)
+        self.assertAlmostEqual(center_of_mass[2], -0.0000, 3)
+
+    def test_get_moment_of_inertia_tensor(self):
+        """Test calculating the moment of inertia tensor"""
+        symbols = ['O', 'C', 'C', 'H', 'H', 'H', 'H', 'H', 'H']
+        coords = np.array([[1.28706525, 0.52121353, 0.04219198],
+                           [0.39745682, -0.35265044, -0.63649234],
+                           [0.36441173, -1.68197093, 0.08682400],
+                           [-0.59818222, 0.10068325, -0.65235399],
+                           [0.74799641, -0.48357798, -1.66461710],
+                           [0.03647269, -1.54932006, 1.12314420],
+                           [-0.31340646, -2.38081353, -0.41122551],
+                           [1.36475837, -2.12581592, 0.12433596],
+                           [2.16336803, 0.09985803, 0.03295192]], np.float64)
+        tensor = get_moment_of_inertia_tensor(coords=coords, symbols=symbols)
+        expected_tensor = [[50.24197604, -15.43600683, -3.07977736],
+                           [-15.43600683, 22.20416597, 2.5935549],
+                           [-3.07977736, 2.5935549, 55.49144794]]
+        np.testing.assert_almost_equal(tensor, expected_tensor)
+
+    def test_get_principal_moments_of_inertia(self):
+        """Test calculating the principal moments of inertia"""
+        numbers = [6, 6, 8, 1, 1, 1, 1, 1, 1]
+        coords = np.array([[1.235366, -0.257231, -0.106315],
+                           [0.083698, 0.554942, 0.046628],
+                           [-1.210594, -0.239505, -0.021674],
+                           [0.132571, 1.119728, 0.987719],
+                           [0.127795, 1.278999, -0.769346],
+                           [-1.272620, -0.962700, 0.798216],
+                           [-2.074974, 0.426198, 0.055846],
+                           [-1.275744, -0.785745, -0.965493],
+                           [1.241416, -0.911257, 0.593856]], np.float64)
+        principal_moments_of_inertia = get_principal_moments_of_inertia(coords=coords, numbers=numbers)[0]
+        expected_principal_moments_of_inertia = [60.98026894, 53.83156297, 14.48858465]
+        for moment, expected_moment in zip(principal_moments_of_inertia, expected_principal_moments_of_inertia):
+            self.assertAlmostEqual(moment, expected_moment)
+
+        symbols = ['N', 'O', 'O']  # test a linear molecule
+        coords = np.array([[0.000000, 0.000000, 1.106190],
+                           [0.000000, 0.000000, -0.072434],
+                           [0.000000, 0.000000, -1.191782]], np.float64)
+        with self.assertRaises(InputError):
+            get_principal_moments_of_inertia(coords=coords, numbers=numbers)
+        principal_moments_of_inertia, axes = get_principal_moments_of_inertia(coords=coords, symbols=symbols)
+        expected_principal_moments_of_inertia = [39.4505153, 39.4505153, 0.0]
+        expected_axes = [[1, 0, 0], [0, 1, 0], [0, 0, 1]]
+        for moment, expected_moment in zip(principal_moments_of_inertia, expected_principal_moments_of_inertia):
+            self.assertAlmostEqual(moment, expected_moment)
+        for axis, expected_axis in zip(axes, expected_axes):
+            for entry, expected_entry in zip(axis, expected_axis):
+                self.assertAlmostEqual(entry, expected_entry)
+        self.assertIsInstance(principal_moments_of_inertia, tuple)
+        self.assertIsInstance(axes, tuple)
 
 ################################################################################
 
+
 if __name__ == '__main__':
     unittest.main(testRunner=unittest.TextTestRunner(verbosity=2))

arkane/data/terachem/ethane_coords.xyz

@@ -0,0 +1,8 @@
+6
+coordinates
+C       0.66409651    0.00395265    0.07100793
+C      -0.66409647   -0.00395253   -0.07100790
+H       1.24675866    0.88983869   -0.16137840
+H       1.19483972   -0.87530680    0.42244414
+H      -1.19483975    0.87530673   -0.42244421
+H      -1.24675868   -0.88983873    0.16137844