Energy of the fundamental level of an anharmonic oscillator in the strong-coupling limit

A nonperturbative method of calculating functional integrals is developed. The effectiveness of its application is illustrated for the example of calculating the energy of the fundamental level of an anharmonic oscillator.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 64–69, July, 1990.It remains to thank A. A. Afonin, V. N. Kapshai, V. N. Starikov, and V. G. Teplyakov for interest in the work and useful discussions of the results.