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MaxEntVAMPNet

Codes for Active Learning of the Conformational Ensemble of Proteins using Maximum Entropy VAMPNets.

Figure illustrates Shannon entropy maxima occurring at lobe transition interface in the Lorenz system.

Code to generate this figure: https://colab.research.google.com/drive/1lQTe7L1khPvoo5F_8W6IP5JEP5Ikf2CT?usp=sharing

Citation

If using the code in this repository, please include the following in your citations: https://pubs.acs.org/doi/10.1021/acs.jctc.3c00040

Environment

The clean_env.yml file can be used with conda to recreate the environment used while conducting the research.

conda env create -f clean_env.yml

However, solving this environment with conda can take a very long time. For this reason, we suggest starting from a conda environment with a working installation of pytorch and then installing the remaining packages listed in the .yml file:

conda create -n maxent # Create a new environment 
conda install pytorch torchvision torchaudio pytorch-cuda=11.7 -c pytorch -c nvidia # Installs pytorch in the current conda env (valid as of Apr 2023)
conda install -c conda-forge deeptime dill mdtraj openmm seaborn tqdm

To use jupyter notebooks, you can optionally install the jupyter package as well.

Description

This repository contains codes implementing different adaptive sampling methods (AdaptiveSampling.py, EntropyBased.py, Reap.py, VaeReap.py, VampNetReap.py, VampReap.py) and supporting objects or methods (Agent.py, Simulations.py, utils.py).

The examples directory contains usage examples to run molecular dynamics simulations. See the README in the directory for more details. Check the Short example down below for a general idea of how to use the codes.

Methods

There are many different adaptive sampling methods implemented in this repository as Python classes. Check the table below for a quick summary of the main ones. The kinetic models correspond to those implemented in deeptime.

Short example

The Python classes offered here provide functionalities that correspond to different aspects of executing an adaptive sampling run.

A Simulation object packages the necessary information of the system to run the simulations. Currently it only works with OpenMM and the trajectories are performed serially (intended for testing purposes). You can override the methods in the corresponding class or contribute your own to add parallelization or use a different MD engine.

The Agent object provides the scoring method used to rank structures for seeding of new trajectories.

The FileHandler object organizes the files that will be created by the run. The user should not need to interact with this class.

Finally, the AdaptiveSampling class implements the selection strategy and takes an instance of the kinetic model to be trained.

The following is a minimal example (may need some small modifications) for running 10 rounds of simulation of the villin headpiece protein in implicit solvent using the MaxEnt method.

import numpy as np
import mdtraj as md
import torch.nn as nn
from deeptime.util.torch import MLP
from Simulation import ImplicitSim
from EntropyBased import EntropyBasedSampling

# Define simulation system (simulation details hidden under the hood)
system = ImplicitSim("../villin.pdb", platform="CPU")

# Define features --> All alpha C pairwise distances (residues separated by 3 amino acids or more)
indices = np.asarray([ [i, j] for i in range(35) for j in range(i+3, 35) ])
features = [ lambda x, i=idx: md.compute_contacts(x, scheme='ca', contacts=[i])[0].flatten() for idx in indices ]

# Define some settings
tstep = 2e-15  # 2 fs is the default timestep --> Used to calculate traj_len
traj_len = int(10e-9 / tstep)  # 10 ns per individual trajectory
save_rate = int(traj_len / 1e4)  # Save 10000 frames per traj
trajs_per_round = 10  # 10 trajectories per round
num_rounds = 10  # 10*10*10 ns = 1 us total simulated time
ndim = 8  # 8 output states
lagtime = 100  # 100*save_rate*tstep = 10 ps

# Define initial state
init_states = [
    dict(fname="../villin.pdb",
         frame_idx=0,
         top_file=system.top_file,
         agent_idx=0), # Only single agent for MaxEnt
]



# Silence deprecation warning
def softmax():
    return nn.Softmax(dim=0)

vnet_lobe = MLP(units=[len(features), 512, 256, 128, 64, 32, 16, ndim], nonlinearity=nn.ReLU, output_nonlinearity=softmax)

# Initialize adaptive sampling object

adaptive_run = EntropyBasedSampling(system=system,
                                    root="./",
                                    basename="villin",
                                    save_rate=save_rate,
                                    features=features,
                                    save_info=True,
                                    lagtime=lagtime,
                                    device='cpu',
                                    vnet_batch_size=1024,
                                    vnet_num_threads=8,
                                    vnet_lobe=vnet_lobe,
                                    vnet_output_states=ndim)  # Using default values for some parameters
# Obtain initial data
adaptive_run.collect_initial_data(init_states, n_steps=traj_len, n_repeats=1)

# Run adaptive sampling runs
for i in range(num_rounds):
  adaptive_run.run_round(n_select=trajs_per_round, n_steps=traj_len, n_repeats=1)