Use of Trotter Theorem in Path Integral Molecular Dynamics

In summary, the conversation discusses difficulties in proving step 8.3 of the path integral formulation of molecular dynamics. The potential operators are diagonal in the x basis, leading to the need to evaluate an integral involving the exponential of the T operator. By completing the square and integrating over the shifted momentum, a Gaussian function is obtained. The specifics of the constants involved are left open for further calculation.
  • #1
jelathome
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I am unable to prove step 8.3 in this proof of the path integral formulation of molecular dynamics
https://files.nyu.edu/mt33/public/jpc_feat/node11.html

Any help would be much appreciated.
 
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  • #2
The exponentials containing the U's are clear, I suppose? The potential operators are diagonal in the x basis so you are left with the exponential of the T operator between x(s) and x(x+1). Insert momentum eigenstates. The T operator in the exponent becomes proportional to p^2 and ##<p|x>\propto \exp(ipx)##. So you have to evaluate something like ##\int dp \exp(Cp^2+ip(x(s)-x(s+1)))##. Complete the square and integrate over the shifted p. You get the Gaussian ## \exp(-C'(x(s)-x(s+1))^2)##. You are free to work out all the constants I left open.
 
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Related to Use of Trotter Theorem in Path Integral Molecular Dynamics

1. What is Trotter Theorem and how is it used in Path Integral Molecular Dynamics?

Trotter Theorem is a mathematical concept that allows for the approximation of the quantum evolution operator in a path integral formulation. In Path Integral Molecular Dynamics, it is used to compute the quantum mechanical properties of a system by breaking down the system into smaller, classical-like systems that can be more easily simulated.

2. Why is Trotter Theorem important in Path Integral Molecular Dynamics?

Trotter Theorem is important in Path Integral Molecular Dynamics because it allows for the efficient simulation of quantum mechanical systems, which would otherwise be computationally expensive. This enables researchers to study the behavior of complex systems and make predictions about their properties.

3. What are the limitations of using Trotter Theorem in Path Integral Molecular Dynamics?

One limitation of using Trotter Theorem in Path Integral Molecular Dynamics is that it is an approximation and therefore may introduce errors in the simulation results. Additionally, it may not be applicable in all cases, such as highly non-linear systems, and may require additional corrections or modifications to accurately simulate certain systems.

4. Are there any alternative methods to using Trotter Theorem in Path Integral Molecular Dynamics?

Yes, there are alternative methods to using Trotter Theorem in Path Integral Molecular Dynamics. Some examples include the use of higher-order approximations, such as the Suzuki-Trotter decomposition, or the use of different integration techniques, such as the split-operator method.

5. How does the use of Trotter Theorem in Path Integral Molecular Dynamics impact the understanding of quantum systems?

The use of Trotter Theorem in Path Integral Molecular Dynamics has greatly advanced our understanding of quantum systems by allowing for the simulation of complex systems that were previously not feasible. It has also provided insights into the behavior and properties of these systems, leading to new discoveries and advancements in various fields, such as chemistry, physics, and materials science.

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