Detailed Description
Lamellar order parameter as a collective variable to study phase transitions in block copolymer systems.
This collective variable is based on the Fourier modes of concentration or composition fluctuations.
The value of the collective variable 
is given by
![\[ s = V^{-1} \sum_{i = 1}^n \sum_{j = 1}^N a(type_j) \cos(\mathbf{q}_i\mathbf{r_j} + \phi_i), \]](form_9.png)
where
is the number of modes supplied
is the number of particles
is the system volume
is the wave vector associated with mode 
,
its phase shift,
is the mode coefficient for a particle of type 
.
The force on particle i is calculated as 
.
Example:
In a diblock copolymer melt constructed from monomers of types A and B, use
metadynamics.cv.lamellar(sigma=.05,mode=dict(A=1.0, B=-1.0), lattice_vectors=[(0,0,3)],phi=[0.0])
to define the order parameter for a Fourier mode along the (003) direction, with mode coefficients of +1 and -1 for A and B monomers. The width of Gaussians deposited is sigma=0.05. The phase shift is zero.
Logging:
The log name of this collective variable used by the command analyze.log is cv_lamellar.
Inheritance diagram for lamellar:
Public Member Functions | |
| def | __init__ |
| Construct a lamellar order parameter. | |
| def | update_coeffs |
 Public Member Functions inherited from _collective_variable | |
| def | __init__ |
| def | enable_grid |
| Sets grid mode for this collective variable. | |
Public Attributes | |
| cpp_force | |
| Public Attributes inherited from _collective_variable | |
| sigma | |
| cv_min | |
| cv_max | |
| num_points | |
| use_grid | |
Constructor & Destructor Documentation
| def __init__ | ( | self, | |
| sigma, | |||
| mode, | |||
| lattice_vectors, | |||
| phi, | |||
name = None |
|||
| ) |
Construct a lamellar order parameter.
- Parameters:
-
sigma Width of deposited Gaussians mode Per-type list (dictionary) of mode coefficients lattice_vectors List of reciprocal lattice vectors (Miller indices) for every mode phi Per-mode list of phase shifts name Name given to this collective variable
The documentation for this class was generated from the following file:
- cv.py
