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Commit c117923f authored by cmaffeo2's avatar cmaffeo2
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Added exclusions andnd angles to segmentmodel

parent d3361ce8
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nonbonded.py
View file @ c117923f
......@@ -67,7 +67,7 @@ class HarmonicPotential():
self.prefix = prefix
self.periodic = False
self.type_ = "None"
self.kscale_ = None
self.kscale_ = None # only used for
def filename(self):
# raise NotImplementedError("Not implemented")
......@@ -90,8 +90,9 @@ class HarmonicPotential():
u = 0.5*self.k*dr**2
if self.maxForce is not None:
assert(self.maxForce > 0)
maxForce = self.maxForce
if maxForce is not None:
assert(maxForce > 0)
f = np.diff(u)/np.diff(r)
f[f>maxForce] = maxForce
f[f<-maxForce] = -maxForce
......@@ -121,15 +122,15 @@ class HarmonicBond(HarmonicPotential):
self.kscale_ = 1.0
class HarmonicAngle(HarmonicPotential):
def __init__(self, k, r0, rRange=(0,50), resolution=0.1, maxForce=None, prefix="potentials/"):
def __init__(self, k, r0, rRange=(0,181), resolution=0.1, maxForce=None, prefix="potentials/"):
HarmonicPotential.__init__(self, k, r0, rRange, resolution, maxForce, prefix)
self.type_ = "angle"
self.kscale_ = (180.0/pi)**2
self.kscale_ = (180.0/np.pi)**2
class HarmonicDihedral(HarmonicPotential):
def __init__(self, k, r0, rRange=(0,50), resolution=0.1, maxForce=None, prefix="potentials/"):
def __init__(self, k, r0, rRange=(-180,180), resolution=0.1, maxForce=None, prefix="potentials/"):
HarmonicPotential.__init__(self, k, r0, rRange, resolution, maxForce, prefix)
self.periodic = True
self.type_ = "dihedral"
self.kscale_ = (180.0/pi)**2
self.kscale_ = (180.0/np.pi)**2
segmentmodel.py
View file @ c117923f
......@@ -94,7 +94,7 @@ class Segment(ConnectableElement, Group):
ret.append( tmp )
return ret
def get_beads_before_bead(self, bead, number, inclusive=True):
def get_beads_before_bead(self, bead, number, inclusive=False):
## Assume that consecutive beads in self.children are bonded
i = self.children.index(bead)
l = len(self.children)
......@@ -105,7 +105,7 @@ class Segment(ConnectableElement, Group):
if inclusive: start = 0
return [self.children[i-j] for j in range(start,number)]
def get_beads_after_bead(self, bead, number, inclusive=True):
def get_beads_after_bead(self, bead, number, inclusive=False):
## Assume that consecutive beads in self.children are bonded
i = self.children.index(bead)
l = len(self.children)
......@@ -116,6 +116,10 @@ class Segment(ConnectableElement, Group):
if inclusive: start = 0
return [self.children[i+i] for j in range(start,number)]
# def get_bead_pairs_within(self, cutoff):
# for b1,b2 in self.get_all_consecutive_beads(self, number)
def _generate_beads(self, bead_model, max_nts_per_bead=4):
""" Generate beads (positions, types, etcl) and bonds, angles, dihedrals, exclusions """
......@@ -334,39 +338,68 @@ class SegmentModel(ArbdModel):
if c.type_ == "intrahelical":
b1,b2 = [loc.particle for loc in (c.A,c.B)]
for b in (b1,b2): assert( b is not None )
## TODO: make this code more robust
## TODO: find bug that makes things be out of order
try:
b0 = s1.get_beads_before_bead(b1,1)[0]
b0 = s1.get_beads_before_bead(b1,1)
assert(len(b0) == 1)
b0 = b0[0]
assert( b0 is not None )
ret.append( [b0,b1,b2] )
except:
...
try:
b0 = s1.get_beads_after_bead(b1,1)[0]
b0 = s1.get_beads_after_bead(b1,1)
assert(len(b0) == 1)
b0 = b0[0]
assert( b0 is not None )
ret.append( [b2,b1,b0] )
except:
...
try:
b3 = s2.get_beads_before_bead(b2,1)[0]
b3 = s2.get_beads_before_bead(b2,1)
assert(len(b3) == 1)
b3 = b3[0]
assert( b3 is not None )
ret.append( [b3,b2,b1] )
except:
...
try:
b3 = s2.get_beads_after_bead(b2,1)[0]
b3 = s2.get_beads_after_bead(b2,1)
assert(len(b3) == 1)
b3 = b3[0]
assert( b3 is not None )
ret.append( [b1,b2,b3] )
except:
...
return ret
# def _get_intrahelical_bead_pairs_within(self, cutoff):
# dist = dict()
# for b1,b2 in self._get_intrahelical_beads:
# dist(b1,b2)
# ret = []
# for s in self.segments:
# ret.extend( s.get_bead_pairs_within(cutoff) )
# for s1 in self.segments:
# for c in s1.connections:
# if c.A.container != s1: continue
# s2 = c.B.container
# if c.type_ == "intrahelical":
# ret
def _get_potential(self, type_, kSpring, d):
key = (type_,kSpring,d)
if key not in self._bonded_potential:
if type_ == "bond":
self._bonded_potential[key] = HarmonicBond(kSpring,d)
elif type_ == "angle":
self._bonded_potential[key] = HarmonicAngle(kSpring,d)
self._bonded_potential[key] = HarmonicAngle(kSpring,d) # , resolution = 1, maxForce=0.1)
elif type_ == "dihedral":
self._bonded_potential[key] = HarmonicDihedral(kSpring,d)
else:
......@@ -415,8 +448,8 @@ class SegmentModel(ArbdModel):
beadtype_s[key] = b.type_ = t
""" Add intrahelical potentials """
## First replace intrahelical bonds
""" Add intrahelical bond potentials """
dists = dict() # built for later use
for b1,b2 in self._get_intrahelical_beads():
if b1.parent == b2.parent:
sep = 0.5*(b1.num_nts+b2.num_nts)
......@@ -424,19 +457,83 @@ class SegmentModel(ArbdModel):
else:
sep = 1
parent = self
conversion = 0.014393265 # units "pN/AA" kcal_mol/AA^2
if b1.type_.name[0] == "D" and b1.type_.name[0] == "D":
k = 10.0/np.sqrt(sep) # TODO: determine from simulations
elastic_modulus = 1000 # pN http://markolab.bmbcb.northwestern.edu/marko/Cocco.CRP.02.pdf
d = 3.4*sep
k = conversion*elastic_modulus/d
else:
## TODO: get correct numbers from ssDNA model
k = 1.0/np.sqrt(sep)
## TODO: get better numbers our ssDNA model
elastic_modulus = 800 # pN http://markolab.bmbcb.northwestern.edu/marko/Cocco.CRP.02.pdf
d = 5*sep
k = conversion*elastic_modulus/d
if b1 not in dists:
dists[b1] = []
if b2 not in dists:
dists[b2] = []
dists[b1].append([b2,sep])
dists[b2].append([b1,sep])
# dists[[b1,b2]] = dists[[b2,b1]] = sep
bond = self.get_bond_potential(k,d)
parent.add_bond( b1, b2, bond, exclude=True )
""" Add intrahelical angle potentials """
for b1,b2,b3 in self._get_intrahelical_angle_beads():
sep = 0
if b1.parent == b2.parent:
sep += 0.5*(b1.num_nts+b2.num_nts)
else:
sep += 1
if b2.parent == b3.parent:
sep += 0.5*(b2.num_nts+b3.num_nts)
else:
sep += 1
if b1.parent == b2.parent and b2.parent == b3.parent:
parent = b1.parent
else:
parent = self
kT = 0.58622522 # kcal/mol
if b1.type_.name[0] == "D" and b2.type_.name[0] == "D" and b3.type_.name[0] == "D":
## <cos(q)> = exp(-s/Lp) = integrate( x^4 exp(-A x^2) / 2, {x, 0, pi} ) / integrate( x^2 exp(-A x^2), {x, 0, pi} )
## <cos(q)> ~ 1 - 3/4A
## where A = k_spring / (2 kT)
k = 1.5 * kT * (1.0 / (1-np.exp(-float(sep)/147))) * 0.00030461742; # kcal_mol/degree^2
else:
## TODO: get correct number from ssDNA model
k = 1.5 * kT * (1.0 / (1-np.exp(-float(sep)/3))) * 0.00030461742; # kcal_mol/degree^2
# k *= 1e-6
angle = self.get_angle_potential(k,180)
parent.add_angle( b1, b2, b3, angle )
""" Add intrahelical exclusions """
beads = dists.keys()
def _recursively_get_beads_within(b1,d,done=[]):
ret = []
for b2,sep in dists[b1]:
if b2 in done: continue
if sep < d:
ret.append( b2 )
done.append( b2 )
tmp = _recursively_get_beads_within(b2, d-sep, done)
if len(tmp) > 0: ret.extend(tmp)
return ret
exclusions = set()
for b1 in beads:
exclusions.update( [(b1,b) for b in _recursively_get_beads_within(b1, 20, done=[b1])] )
for b1,b2 in exclusions:
if b1.parent == b2.parent:
parent = b1.parent
else:
parent = self
parent.add_exclusion( b1, b2 )
""" Add connection potentials """
## TODO
......@@ -449,39 +546,3 @@ class SegmentModel(ArbdModel):
# r
# ...
if __name__ == "__main__":
seg1 = DoubleStrandedSegment("strand", num_nts = 46)
seg2 = SingleStrandedSegment("strand",
start_position = seg1.end_position + np.array((1,0,1)),
num_nts = 12)
seg3 = SingleStrandedSegment("strand",
start_position = seg1.start_position + np.array((-1,0,-1)),
end_position = seg1.end_position + np.array((-1,0,1)),
num_nts = 128)
seg1.start3
seg1.start5
seg1.end3
seg1.end5
seg1.connect_end3(seg2)
seg1.connect_end5(seg3)
seg1.connect_start3(seg3)
model = SegmentModel( [seg1, seg2, seg3],
dimensions=(5000,5000,5000),
)
model.useNonbondedScheme( nbDnaScheme )
model.simulate( outputPrefix = 'strand-test', outputPeriod=1e4, numSteps=1e6, gpu=1 )
# seg = SingleStrandedSegment("strand", num_nts = 21)
# generate_bead_model( [seg] )
# for b in seg:
# print(b.num_nts, b.position)
segmentmodel_example.py
View file @ c117923f
......@@ -17,12 +17,12 @@ if __name__ == "__main__":
seg1 = DoubleStrandedSegment("strand", num_nts = 46)
seg2 = SingleStrandedSegment("strand",
start_position = seg1.end_position + np.array((1,0,1)),
start_position = seg1.end_position + np.array((5,0,5)),
num_nts = 12)
seg3 = SingleStrandedSegment("strand",
start_position = seg1.start_position + np.array((-1,0,-1)),
end_position = seg1.end_position + np.array((-1,0,1)),
start_position = seg1.start_position + np.array((-5,0,-5)),
end_position = seg1.end_position + np.array((-5,0,5)),
num_nts = 128)
seg1.start3
......@@ -37,5 +37,6 @@ if __name__ == "__main__":
model = SegmentModel( [seg1, seg2, seg3],
dimensions=(5000,5000,5000),
)
model.useNonbondedScheme( nbDnaScheme )
model.simulate( outputPrefix = 'strand-test', outputPeriod=1e4, numSteps=1e6, gpu=1 )
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