Quantum computing thermodynamic observables of a chemical system

Abstract

Techniques regarding determining thermodynamic observables of a chemical system are provided. For example, one or more embodiments described herein can include a system, which can comprise a memory that can store computer executable components. The system can also include a processor, operably coupled to the memory, and that can execute the computer executable components stored in the memory. The computer executable components can include a potential energy component that can fit a potential energy function to a computed potential energy surface of a molecule. The computer executable components can also include a vibrational mode component that can compute an intramolecular vibrational mode of the molecule based on the potential energy surface fitted with the potential energy function. Also, the computer executable components can include a partition component that can compute a partition function based on the intramolecular vibrational mode.

What is claimed is: 
     
         1 . A system, comprising:
 a memory; and   a processor, operably coupled to the memory, wherein the processor executes operations that comprise:
 evaluating a potential energy surface of a molecule by executing a VQE algorithm; and 
 fitting a potential energy function to the potential energy surface of the molecule, 
 wherein the potential energy function is parameterized using a range of VQE calculations across a range of bond lengths of the surface molecule. 
   
     
     
         2 . The system of  claim 1 , wherein the operations further comprise:
 computing a partition function based on an intramolecular vibrational mode of the molecule, which intramolecular vibrational mode is based on the fitted potential energy surface.   
     
     
         3 . The system of  claim 1 , wherein the operations further comprise:
 executing the VQE algorithm based on a Born-Oppenheimer approximation.   
     
     
         4 . The system of  claim 1 , wherein the operations further comprise:
 executing an optimization algorithm that is used in the execution of the VQE algorithm,   wherein the optimization algorithm implements an adaptive termination process.   
     
     
         5 . The system of  claim 1 , wherein the potential energy function comprises a Morse potential function. 
     
     
         6 . The system of  claim 2 , wherein the operations further comprise:
 computing a thermodynamic observable of the molecule based on the partition function.   
     
     
         7 . A computer-implemented method, comprising:
 evaluating, by a system operably coupled to a processor, a potential energy surface of a molecule by executing a variational quantum eigensolver (VQE) algorithm;   fitting, by the system, a potential energy function to the potential energy surface of the molecule; and   parameterizing, by the system, the potential energy function using a range of VQE calculations across a range of bond lengths of the surface molecule.   
     
     
         8 . The computer-implemented method of  claim 7 , further comprising:
 computing, by the system, a partition function based on an intramolecular vibrational mode of the molecule, which intramolecular vibrational mode is based on the fitted potential energy surface.   
     
     
         9 . The computer-implemented method of  claim 7 , further comprising:
 executing, by the system, the VQE algorithm based on a Born-Oppenheimer approximation.   
     
     
         10 . The computer-implemented method of  claim 7 , further comprising:
 executing, by the system, an optimization algorithm that is used in the execution of the VQE algorithm,   wherein the optimization algorithm implements an adaptive termination process.   
     
     
         11 . The computer-implemented method of  claim 7 , wherein the potential energy function comprises a Morse potential function. 
     
     
         12 . The computer-implemented method of  claim 8 , further comprising:
 computing, by the system, a thermodynamic observable of the molecule based on the partition function.   
     
     
         13 . A computer program product for utilizing quantum computing to determine a thermodynamic observable, the computer program product comprising a non-transitory computer readable medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to:
 evaluate, by the processor, a potential energy surface of a molecule by executing a variational quantum eigensolver (VQE) algorithm;   fit, by the processor, a potential energy function to the potential energy surface of the molecule; and   parameterize, by the processor, the potential energy function using a range of VQE calculations across a range of bond lengths of the surface molecule.   
     
     
         14 . The computer program product of  claim 13 , wherein the program instructions further cause the processor to:
 compute, by the processor, a partition function based on an intramolecular vibrational mode of the molecule, which intramolecular vibrational mode is based on the fitted potential energy surface.   
     
     
         15 . The computer program product of  claim 13 , wherein the program instructions further cause the processor to:
 execute, by the processor, the VQE algorithm based on a Born-Oppenheimer approximation.   
     
     
         16 . The computer program product of  claim 13 , wherein the program instructions further cause the processor to:
 execute, by the processor, an optimization algorithm that is used in the execution of the VQE algorithm,   wherein the optimization algorithm implements an adaptive termination process.   
     
     
         17 . The computer program product of  claim 13 , wherein the potential energy function comprises a Morse potential function. 
     
     
         18 . The computer program product of  claim 14 , wherein the program instructions further cause the processor to:
 compute, by the processor, a thermodynamic observable of the molecule based on the partition function.   
     
     
         19 . A system, comprising:
 a memory; and   a processor, operably coupled to the memory, wherein the processor executes operations that comprise:
 executing a VQE algorithm on a quantum computer to compute a potential energy surface of a molecule; 
 fitting a potential energy function to the potential energy surface of the molecule, 
 wherein fitting the potential energy function comprises employing a potential energy loss function as a parameterized potential energy surface; 
 parameterizing the potential energy loss function using a set of parameters of a plurality of VQE calculations across a range of bond lengths of the molecule; 
 computing an intramolecular vibrational mode of the molecule based on the potential energy surface fitted with the potential energy loss function; and 
 computing a partition function based on the intramolecular vibrational mode. 
   
     
     
         20 . The system of  claim 19 , wherein the operations further comprise:
 executing the VQE algorithm based on a Born-Oppenheimer approximation.   
     
     
         21 . The system of  claim 19 , wherein the operations further comprise:
 computing a thermodynamic observable of the molecule based on the partition function.   
     
     
         22 . A system, comprising:
 a memory; and   a processor, operably coupled to the memory, wherein the processor executes operations that comprise:
 executing a variational quantum eigensolver algorithm on a quantum device to compute a Born-Oppenheimer potential energy surface of a molecule; and 
 computing a partition function based on the Born-Oppenheimer potential energy surface of the molecule, 
 wherein the computing utilizes a parameterized molecular potential energy function that mitigates noise inherent to the quantum device that executed the variational quantum eigensolver algorithm, 
 wherein the parameterized molecular potential energy function comprises a potential energy loss function employed for a parameterized potential energy surface of the molecule, and 
 wherein the potential energy loss function is parameterized using a set of parameters of a plurality of VQE calculations across a range of bond lengths of the molecule. 
   
     
     
         23 . The system of  claim 22 , wherein the parameterized molecular potential energy function accounts for uneven spacing in vibrational energy levels in the molecule. 
     
     
         24 . The system of  claim 22 , wherein the operations further comprise:
 computing an intramolecular vibrational mode based on the parameterized the molecular potential energy function; and   computing the partition function based on the intramolecular vibrational mode.   
     
     
         25 . The system of  claim 22 , wherein the operations further comprise:
 computing a thermodynamic observable based on the partition function.